[PATCHv2 0/1] add git-p4 unshelve command

[PATCHv2 0/1] add git-p4 unshelve command

[Luke Diamand]

This is another attempt to make a "git p4 unshelve" command.

Unshelving in p4 is a bit like a cross between cherry-pick
and "am", and is very commonly used for review.

This command helps git users who want to try out a shelved
p4 change from some other repo:

e.g.

   $ git p4 unshelve 12345
   unshelved CL12345 into refs/remotes/p4/unshelved/12345
   $ git show refs/remotes/p4/unshelved/12345

I abandoned an earlier attempt because it seemed like there
is no way to get around a rather nasty problem: git-p4
just constructs the commit and passes the file contents to
git-fastimport. But there's no easy way to construct the
*prior* commit, because Perforce doesn't record this
information, and so you can end up with other changes
mixed into the unshelved commit - these are the differences
between your tree and the other tree, for each file that
has been modified.

However, I think the command is sufficiently useful that
it's worth supporting anyway, even with that caveat.

I also tried to use "p4 describe" to get the deltas, but
that's very unsatisfactory: I found myself writing a
second-rate version of git's diff tool to try to make
up for the deficiencies in Perforce's diff tool.

It might be possible to reconstruct the missing base
commit information, but that's a reasonably tricky task.

I have incorporated some of the comments from the earlier
review rounds, in particular:

- no longer adds the [git-p4...] annotation in unshelve
- try to use .format() in place of %
- rename the target branch if it already exists

Luke Diamand (1):
  git-p4: add unshelve command

 Documentation/git-p4.txt |  26 ++++++
 git-p4.py                | 171 ++++++++++++++++++++++++++++++---------
 t/t9832-unshelve.sh      |  99 +++++++++++++++++++++++
 3 files changed, 260 insertions(+), 36 deletions(-)
 create mode 100755 t/t9832-unshelve.sh

-- 
2.17.0.392.gdeb1a6e9b7

[PATCH 1/1] git-p4: add unshelve command

[Luke Diamand]

This can be used to "unshelve" a shelved P4 commit into
a git commit.

For example:

  $ git p4 unshelve 12345

The resulting commit ends up in the branch:
   refs/remotes/p4/unshelved/12345

If that branch already exists, it is renamed - for example
the above branch would be saved as p4/unshelved/12345.1.

Caveat:

The unshelving is done against the current "p4/master" branch;
git-p4 uses "p4 print" to get the file contents at the requested
revision, and then fast-import creates a commit relative to p4/master.

Ideally what you would want is for fast-import to create the
commit based on the Perforce "revision" prior to the shelved commit,
but Perforce doesn't have such a concept - to do this, git-p4
would need to figure out the revisions of the individual files
before the shelved changelist, and then construct a temporary
git branch which matched this.

It's possible to do this, but doing so makes this change a lot more
complicated.

This limitation means that if you unshelve a change where some
of the changed files were not based on p4/master, you will get
an amalgam of the change you wanted, and these other changes.

The reference branch can be changed manually with the "--origin"
option.

The change adds a new Unshelve command class. This just runs the
existing P4Sync code tweaked to handle a shelved changelist.

Signed-off-by: Luke Diamand <luke@diamand.org>
---
 Documentation/git-p4.txt |  26 ++++++
 git-p4.py                | 171 ++++++++++++++++++++++++++++++---------
 t/t9832-unshelve.sh      |  99 +++++++++++++++++++++++
 3 files changed, 260 insertions(+), 36 deletions(-)
 create mode 100755 t/t9832-unshelve.sh

diff --git a/Documentation/git-p4.txt b/Documentation/git-p4.txt
index d8c8f11c9f..2d768eec10 100644
--- a/Documentation/git-p4.txt
+++ b/Documentation/git-p4.txt
@@ -164,6 +164,25 @@ $ git p4 submit --shelve
 $ git p4 submit --update-shelve 1234 --update-shelve 2345
 ----
 
+
+Unshelve
+~~~~~~~~
+Unshelving will take a shelved P4 changelist, and produce the equivalent git commit
+in the branch refs/remotes/p4/unshelved/<changelist>.
+
+The git commit is created relative to the current p4/master, so if this
+is behind Perforce itself, it may include more changes than you expected. You can
+change the reference branch with the "--origin" option.
+
+If the target branch in refs/remotes/p4/unshelved already exists, the old one will
+be renamed.
+
+----
+$ git p4 sync
+$ git p4 unshelve 12345
+$ git show refs/remotes/p4/unshelved/12345
+----
+
 OPTIONS
 -------
 
@@ -337,6 +356,13 @@ These options can be used to modify 'git p4 rebase' behavior.
 --import-labels::
 	Import p4 labels.
 
+Unshelve options
+~~~~~~~~~~~~~~~~
+
+--origin::
+    Sets the git refspec against which the shelved P4 changelist is compared.
+    Defaults to p4/master.
+
 DEPOT PATH SYNTAX
 -----------------
 The p4 depot path argument to 'git p4 sync' and 'git p4 clone' can
diff --git a/git-p4.py b/git-p4.py
index 7bb9cadc69..dcf6dc9f4f 100755
--- a/git-p4.py
+++ b/git-p4.py
@@ -316,12 +316,17 @@ def p4_last_change():
     results = p4CmdList(["changes", "-m", "1"], skip_info=True)
     return int(results[0]['change'])
 
-def p4_describe(change):
+def p4_describe(change, shelved=False):
     """Make sure it returns a valid result by checking for
        the presence of field "time".  Return a dict of the
        results."""
 
-    ds = p4CmdList(["describe", "-s", str(change)], skip_info=True)
+    cmd = ["describe", "-s"]
+    if shelved:
+        cmd += ["-S"]
+    cmd += [str(change)]
+
+    ds = p4CmdList(cmd, skip_info=True)
     if len(ds) != 1:
         die("p4 describe -s %d did not return 1 result: %s" % (change, str(ds)))
 
@@ -662,6 +667,12 @@ def gitBranchExists(branch):
                             stderr=subprocess.PIPE, stdout=subprocess.PIPE);
     return proc.wait() == 0;
 
+def gitUpdateRef(ref, newvalue):
+    subprocess.check_call(["git", "update-ref", ref, newvalue])
+
+def gitDeleteRef(ref):
+    subprocess.check_call(["git", "update-ref", "-d", ref])
+
 _gitConfig = {}
 
 def gitConfig(key, typeSpecifier=None):
@@ -2411,6 +2422,7 @@ class P4Sync(Command, P4UserMap):
         self.tempBranches = []
         self.tempBranchLocation = "refs/git-p4-tmp"
         self.largeFileSystem = None
+        self.suppress_meta_comment = False
 
         if gitConfig('git-p4.largeFileSystem'):
             largeFileSystemConstructor = globals()[gitConfig('git-p4.largeFileSystem')]
@@ -2421,6 +2433,18 @@ class P4Sync(Command, P4UserMap):
         if gitConfig("git-p4.syncFromOrigin") == "false":
             self.syncWithOrigin = False
 
+        self.depotPaths = []
+        self.changeRange = ""
+        self.previousDepotPaths = []
+        self.hasOrigin = False
+
+        # map from branch depot path to parent branch
+        self.knownBranches = {}
+        self.initialParents = {}
+
+        self.tz = "%+03d%02d" % (- time.timezone / 3600, ((- time.timezone % 3600) / 60))
+        self.labels = {}
+
     # Force a checkpoint in fast-import and wait for it to finish
     def checkpoint(self):
         self.gitStream.write("checkpoint\n\n")
@@ -2429,7 +2453,7 @@ class P4Sync(Command, P4UserMap):
         if self.verbose:
             print "checkpoint finished: " + out
 
-    def extractFilesFromCommit(self, commit):
+    def extractFilesFromCommit(self, commit, shelved=False, shelved_cl = 0):
         self.cloneExclude = [re.sub(r"\.\.\.$", "", path)
                              for path in self.cloneExclude]
         files = []
@@ -2452,6 +2476,9 @@ class P4Sync(Command, P4UserMap):
             file["rev"] = commit["rev%s" % fnum]
             file["action"] = commit["action%s" % fnum]
             file["type"] = commit["type%s" % fnum]
+            if shelved:
+                file["shelved_cl"] = int(shelved_cl)
+
             files.append(file)
             fnum = fnum + 1
         return files
@@ -2743,7 +2770,16 @@ class P4Sync(Command, P4UserMap):
             def streamP4FilesCbSelf(entry):
                 self.streamP4FilesCb(entry)
 
-            fileArgs = ['%s#%s' % (f['path'], f['rev']) for f in filesToRead]
+            fileArgs = []
+            for f in filesToRead:
+                if 'shelved_cl' in f:
+                    # Handle shelved CLs using the "p4 print file@=N" syntax to print
+                    # the contents
+                    fileArg = '%s@=%d' % (f['path'], f['shelved_cl'])
+                else:
+                    fileArg = '%s#%s' % (f['path'], f['rev'])
+
+                fileArgs.append(fileArg)
 
             p4CmdList(["-x", "-", "print"],
                       stdin=fileArgs,
@@ -2844,11 +2880,15 @@ class P4Sync(Command, P4UserMap):
         self.gitStream.write(details["desc"])
         if len(jobs) > 0:
             self.gitStream.write("\nJobs: %s" % (' '.join(jobs)))
-        self.gitStream.write("\n[git-p4: depot-paths = \"%s\": change = %s" %
-                             (','.join(self.branchPrefixes), details["change"]))
-        if len(details['options']) > 0:
-            self.gitStream.write(": options = %s" % details['options'])
-        self.gitStream.write("]\nEOT\n\n")
+
+        if not self.suppress_meta_comment:
+            self.gitStream.write("\n[git-p4: depot-paths = \"%s\": change = %s" %
+                                (','.join(self.branchPrefixes), details["change"]))
+            if len(details['options']) > 0:
+                self.gitStream.write(": options = %s" % details['options'])
+            self.gitStream.write("]\n")
+
+        self.gitStream.write("EOT\n\n")
 
         if len(parent) > 0:
             if self.verbose:
@@ -3162,10 +3202,10 @@ class P4Sync(Command, P4UserMap):
         else:
             return None
 
-    def importChanges(self, changes):
+    def importChanges(self, changes, shelved=False):
         cnt = 1
         for change in changes:
-            description = p4_describe(change)
+            description = p4_describe(change, shelved)
             self.updateOptionDict(description)
 
             if not self.silent:
@@ -3235,7 +3275,7 @@ class P4Sync(Command, P4UserMap):
                                 print "Parent of %s not found. Committing into head of %s" % (branch, parent)
                             self.commit(description, filesForCommit, branch, parent)
                 else:
-                    files = self.extractFilesFromCommit(description)
+                    files = self.extractFilesFromCommit(description, shelved, change)
                     self.commit(description, files, self.branch,
                                 self.initialParent)
                     # only needed once, to connect to the previous commit
@@ -3300,17 +3340,23 @@ class P4Sync(Command, P4UserMap):
             print "IO error with git fast-import. Is your git version recent enough?"
             print self.gitError.read()
 
+    def openStreams(self):
+        self.importProcess = subprocess.Popen(["git", "fast-import"],
+                                              stdin=subprocess.PIPE,
+                                              stdout=subprocess.PIPE,
+                                              stderr=subprocess.PIPE);
+        self.gitOutput = self.importProcess.stdout
+        self.gitStream = self.importProcess.stdin
+        self.gitError = self.importProcess.stderr
 
-    def run(self, args):
-        self.depotPaths = []
-        self.changeRange = ""
-        self.previousDepotPaths = []
-        self.hasOrigin = False
-
-        # map from branch depot path to parent branch
-        self.knownBranches = {}
-        self.initialParents = {}
+    def closeStreams(self):
+        self.gitStream.close()
+        if self.importProcess.wait() != 0:
+            die("fast-import failed: %s" % self.gitError.read())
+        self.gitOutput.close()
+        self.gitError.close()
 
+    def run(self, args):
         if self.importIntoRemotes:
             self.refPrefix = "refs/remotes/p4/"
         else:
@@ -3497,15 +3543,7 @@ class P4Sync(Command, P4UserMap):
                     b = b[len(self.projectName):]
                 self.createdBranches.add(b)
 
-        self.tz = "%+03d%02d" % (- time.timezone / 3600, ((- time.timezone % 3600) / 60))
-
-        self.importProcess = subprocess.Popen(["git", "fast-import"],
-                                              stdin=subprocess.PIPE,
-                                              stdout=subprocess.PIPE,
-                                              stderr=subprocess.PIPE);
-        self.gitOutput = self.importProcess.stdout
-        self.gitStream = self.importProcess.stdin
-        self.gitError = self.importProcess.stderr
+        self.openStreams()
 
         if revision:
             self.importHeadRevision(revision)
@@ -3585,11 +3623,7 @@ class P4Sync(Command, P4UserMap):
             missingP4Labels = p4Labels - gitTags
             self.importP4Labels(self.gitStream, missingP4Labels)
 
-        self.gitStream.close()
-        if self.importProcess.wait() != 0:
-            die("fast-import failed: %s" % self.gitError.read())
-        self.gitOutput.close()
-        self.gitError.close()
+        self.closeStreams()
 
         # Cleanup temporary branches created during import
         if self.tempBranches != []:
@@ -3721,6 +3755,70 @@ class P4Clone(P4Sync):
 
         return True
 
+class P4Unshelve(Command):
+    def __init__(self):
+        Command.__init__(self)
+        self.options = []
+        self.description = "Unshelve a P4 changelist into a git commit"
+        self.usage = "usage: %prog [options] changelist"
+        self.options += [
+                optparse.make_option("--origin", dest="origin"),
+        ]
+        self.verbose = False
+        self.noCommit = False
+        self.origin = "HEAD"
+        self.destbranch = "refs/remotes/p4/unshelved"
+
+    def run(self, args):
+        if len(args) != 1:
+            return False
+
+        if not gitBranchExists(self.origin):
+            sys.exit("origin branch {} does not exist".format(self.origin))
+
+        sync = P4Sync()
+        changes = args
+        sync.initialParent = self.origin
+
+        # use the first change in the list to construct the branch to unshelve into
+        change = changes[0]
+
+        # if it already exists, rename it
+        branch_name = "{}/{}".format(self.destbranch, change)
+        if gitBranchExists(branch_name):
+            found = True
+            for i in range(0,1000):
+                backup_branch_name = "{}.{}".format(branch_name, i)
+                if not gitBranchExists(backup_branch_name):
+                    gitUpdateRef(backup_branch_name, branch_name) # copy ref to backup
+                    gitDeleteRef(branch_name)
+                    found = True
+                    print("renamed old unshelve branch to {}".format(backup_branch_name))
+                    break
+
+            if not found:
+                sys.exit("gave up trying to rename existing branch {}".format(sync.branch))
+        sync.branch = branch_name
+
+        sync.verbose = self.verbose
+        sync.suppress_meta_comment = True
+
+        print("getting log message from {}".format(self.origin))
+        log = extractLogMessageFromGitCommit("refs/remotes/p4/master")
+        settings = extractSettingsGitLog(log)
+        sync.depotPaths = settings['depot-paths']
+        sync.branchPrefixes = sync.depotPaths
+
+        sync.openStreams()
+        sync.loadUserMapFromCache()
+        sync.silent = True
+        sync.importChanges(changes, shelved=True)
+        sync.closeStreams()
+
+        print("unshelved CL{} into {}".format(change, branch_name))
+
+        return True
+
 class P4Branches(Command):
     def __init__(self):
         Command.__init__(self)
@@ -3775,7 +3873,8 @@ commands = {
     "rebase" : P4Rebase,
     "clone" : P4Clone,
     "rollback" : P4RollBack,
-    "branches" : P4Branches
+    "branches" : P4Branches,
+    "unshelve" : P4Unshelve,
 }
 
 
diff --git a/t/t9832-unshelve.sh b/t/t9832-unshelve.sh
new file mode 100755
index 0000000000..332d30ece9
--- /dev/null
+++ b/t/t9832-unshelve.sh
@@ -0,0 +1,99 @@
+#!/bin/sh
+
+last_shelved_change() {
+	p4 changes -s shelved -m1 | cut -d " " -f 2
+}
+
+test_description='git p4 unshelve'
+
+. ./lib-git-p4.sh
+
+test_expect_success 'start p4d' '
+	start_p4d
+'
+
+test_expect_success 'init depot' '
+	(
+		cd "$cli" &&
+		echo file1 >file1 &&
+		p4 add file1 &&
+		p4 submit -d "change 1"
+		: >file_to_delete &&
+		p4 add file_to_delete &&
+		p4 submit -d "file to delete"
+	)
+'
+
+test_expect_success 'initial clone' '
+	git p4 clone --dest="$git" //depot/@all
+'
+
+test_expect_success 'create shelved changelist' '
+	(
+		cd "$cli" &&
+		p4 edit file1 &&
+		echo "a change" >>file1 &&
+		echo "new file" >file2 &&
+		p4 add file2 &&
+		p4 delete file_to_delete &&
+		p4 opened &&
+		p4 shelve -i <<EOF
+Change: new
+Description:
+	Test commit
+
+	Further description
+Files:
+	//depot/file1
+	//depot/file2
+	//depot/file_to_delete
+EOF
+
+	) &&
+	(
+		cd "$git" &&
+		change=$(last_shelved_change) &&
+		git p4 unshelve $change &&
+		git show refs/remotes/p4/unshelved/$change | grep -q "Further description" &&
+		git cherry-pick refs/remotes/p4/unshelved/$change &&
+		test_path_is_file file2 &&
+		test_cmp file1 "$cli"/file1 &&
+		test_cmp file2 "$cli"/file2 &&
+		test_path_is_missing file_to_delete
+	)
+'
+
+test_expect_success 'update shelved changelist and re-unshelve' '
+	test_when_finished cleanup_git &&
+	(
+		cd "$cli" &&
+		change=$(last_shelved_change) &&
+		echo "file3" >file3 &&
+		p4 add -c $change file3 &&
+		p4 shelve -i -r <<EOF &&
+Change: $change
+Description:
+	Test commit
+
+	Further description
+Files:
+	//depot/file1
+	//depot/file2
+	//depot/file3
+	//depot/file_to_delete
+EOF
+		p4 describe $change
+	) &&
+	(
+		cd "$git" &&
+		change=$(last_shelved_change) &&
+		git p4 unshelve $change &&
+		git diff refs/remotes/p4/unshelved/$change.0 refs/remotes/p4/unshelved/$change | grep -q file3
+	)
+'
+
+test_expect_success 'kill p4d' '
+	kill_p4d
+'
+
+test_done
-- 
2.17.0.392.gdeb1a6e9b7

Re: [PATCH 1/1] git-p4: add unshelve command

[Luke Diamand]

On 13 May 2018 at 14:52, Merland Romain <merlorom@yahoo.fr> wrote:
> Hello Luke,
>
> Very interseting
> This is indeed an option we are waiting since the introduction of option --shelve for git p4 submit
> What I like most in your approach is the preservation of link to p4/master inducing small changes of git-p4 existing functions already heavily tested.
> Also I like the dedicated branch you create, it is cleaner and then we can cherry-pick in other git branches.

Thanks, I'd be interested to know how you get on with it!

> We made some basic tries on our side, just adding an option --unshelve to P4Submit (for simplicity, but I like much more your P4Unshelve class)
> and trying to use the diff of p4 to generate a patch when possible, then apply it in the current git branch on top of HEAD.
> Here it is, hope it can help a bit.
> Note it also uses p4 print -o for binary files.

I did try something like this earlier this year (if you look in the
archives you'll find it) but I found that it was getting quite
complicated trying to construct a sensible looking patch file from the
output of p4 describe. Better to let git's existing tools do that, as
they're going to be better than any half-baked attempt I might manage
in Python!

Thanks!
Luke



>
> diff --git a/git-p4.py b/git-p4.py
> index f4a6f3b4c..b466b46e1 100755
> --- a/git-p4.py
> +++ b/git-p4.py
> @@ -1353,6 +1353,8 @@ class P4Submit(Command, P4UserMap):
>                                       metavar="CHANGELIST",
>                                       help="update an existing shelved changelist, implies --shelve, "
>                                             "repeat in-order for multiple shelved changelists"),
> +                optparse.make_option("--unshelve", dest="unshelve",
> +                                     help="unshelve speficied ChangeList into current BRANCH."),
>                  optparse.make_option("--commit", dest="commit", metavar="COMMIT",
>                                       help="submit only the specified commit(s), one commit or xxx..xxx"),
>                  optparse.make_option("--disable-rebase", dest="disable_rebase", action="store_true",
> @@ -1367,6 +1369,7 @@ class P4Submit(Command, P4UserMap):
>          self.dry_run = False
>          self.shelve = False
>          self.update_shelve = list()
> +        self.unshelve = ""
>          self.commit = ""
>          self.disable_rebase = False
>          self.prepare_p4_only = False
> @@ -2083,6 +2086,66 @@ class P4Submit(Command, P4UserMap):
>          if self.clientPath == "":
>              die("Error: Cannot locate perforce checkout of %s in client view" % self.depotPath)
>
> +        # special case of unshelving
> +        # todo: put this code in a class like P4Sync or P4Rebase
> +        if self.unshelve != "":
> +            git_dir = os.getcwd() + '/'
> +            print "Importing shelved CL %s into current git branch %s" % (self.unshelve, self.master)
> +            description = p4_describe(self.unshelve)
> +
> +            # get changed files
> +            files = p4CmdList(['files', "@=%s" % self.unshelve])
> +            editedFiles = []
> +            filesToAdd = []
> +            filesToDelete = []
> +            binaryFiles = []
> +            something_to_commit = False
> +            for f in files:
> +                if not f["depotFile"].startswith(self.depotPath):
> +                    print "WARNING: file %s not in this p4 depot - skipping" % f["depotFile"]
> +                    continue
> +
> +                elif f["action"] == 'delete':
> +                    filesToDelete.append(f)
> +                    something_to_commit = True
> +                elif f["action"] == 'add':
> +                    filesToAdd.append(f)
> +                    something_to_commit = True
> +                elif f["type"] == 'binary':
> +                    binaryFiles.append(f)
> +                    something_to_commit = True
> +                elif f["action"] == 'edit':
> +                    editedFiles.append(f)
> +                    something_to_commit = True
> +
> +                f["clientFile"] = f["depotFile"].replace(self.depotPath,self.clientPath)
> +                f["gitFile"] = f["depotFile"].replace(self.depotPath,git_dir)
> +
> +            if not something_to_commit:
> +                print "Nothing to commit. Exiting"
> +                return True
> +
> +            # get the diff and copy to diff directory
> +            for f in editedFiles:
> +                p4diff = p4_read_pipe(['diff2', '-du', f["depotFile"]+'#'+f["rev"], f["depotFile"]+'@='+self.unshelve])
> +                p4diff = "\n".join(p4diff.split("\n")[1:])
> +                p4diff = '--- '+f["gitFile"]+'\n' + '+++ '+f["gitFile"]+'\n' + p4diff
> +                write_pipe(['patch', '-d/', '-p0'], p4diff)
> +                write_pipe(['git', 'add', '-f', f["gitFile"]], "")
> +            for f in filesToAdd:
> +                p4_write_pipe(['print', '-o', f["gitFile"], f["depotFile"]+'@='+self.unshelve], "")
> +                write_pipe(['git', 'add', '-f', f["gitFile"]], "")
> +            for f in filesToDelete:
> +                os.remove(f["gitFile"])
> +                write_pipe(['git', 'rm', f["gitFile"]], "")
> +            for f in binaryFiles:
> +                p4_write_pipe(['print', '-o', f["gitFile"], f["depotFile"]+'@='+self.unshelve], "")
> +                write_pipe(['git', 'add', '-f', f["gitFile"]], "")
> +
> +            # finalize: commit in git
> +            write_pipe(['git', 'commit', '-m', description["desc"]], "")
> +            return True
> +
>          print "Perforce checkout for depot path %s located at %s" % (self.depotPath, self.clientPath)
>          self.oldWorkingDirectory = os.getcwd()
>
> Romain
>
>
>
> Le samedi 12 mai 2018 à 23:24:48 UTC+2, Luke Diamand <luke@diamand.org> a écrit :
>
>
>
>
>
> This can be used to "unshelve" a shelved P4 commit into
> a git commit.
>
> For example:
>
>   $ git p4 unshelve 12345
>
> The resulting commit ends up in the branch:
>   refs/remotes/p4/unshelved/12345
>
> If that branch already exists, it is renamed - for example
> the above branch would be saved as p4/unshelved/12345.1.
>
> Caveat:
>
> The unshelving is done against the current "p4/master" branch;
> git-p4 uses "p4 print" to get the file contents at the requested
> revision, and then fast-import creates a commit relative to p4/master.
>
> Ideally what you would want is for fast-import to create the
> commit based on the Perforce "revision" prior to the shelved commit,
> but Perforce doesn't have such a concept - to do this, git-p4
> would need to figure out the revisions of the individual files
> before the shelved changelist, and then construct a temporary
> git branch which matched this.
>
> It's possible to do this, but doing so makes this change a lot more
> complicated.
>
> This limitation means that if you unshelve a change where some
> of the changed files were not based on p4/master, you will get
> an amalgam of the change you wanted, and these other changes.
>
> The reference branch can be changed manually with the "--origin"
> option.
>
> The change adds a new Unshelve command class. This just runs the
> existing P4Sync code tweaked to handle a shelved changelist.
>
> Signed-off-by: Luke Diamand <luke@diamand.org>