[RFC/PATCHv3 2/3] git-svn: Warn about changing default for --prefix in Git v2.0

[Johan Herland <johan@herland.net>]

In Git v2.0, we will change the default --prefix for init/clone from
none/empty to "origin/" (which causes SVN-tracking branches to be
placed at refs/remotes/origin/* instead of refs/remotes/*).

This patch warns users about the upcoming change, both in the git-svn
manual page, and on stderr when running init/clone in the "multi-mode"
without providing a --prefix.

Cc: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Johan Herland <johan@herland.net>
---
 Documentation/git-svn.txt     | 11 ++++++-
 git-svn.perl                  | 12 +++++++-
 t/t9117-git-svn-init-clone.sh | 67 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 88 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-svn.txt b/Documentation/git-svn.txt
index ac0c72f..7980c20 100644
--- a/Documentation/git-svn.txt
+++ b/Documentation/git-svn.txt
@@ -86,6 +86,14 @@ COMMANDS
 	(refs/remotes/$remote/*). Setting a prefix is also useful
 	if you wish to track multiple projects that share a common
 	repository.
++
+NOTE: In Git v2.0, the default prefix will CHANGE from "" (no prefix)
+to "origin/". This is done to put SVN-tracking refs at
+"refs/remotes/origin/*" instead of "refs/remotes/*", and make them
+more compatible with how Git's own remote-tracking refs are organized
+(i.e. refs/remotes/$remote/*). You can enjoy the same benefits today,
+by using the --prefix option.
+
 --ignore-paths=<regex>;;
 	When passed to 'init' or 'clone' this regular expression will
 	be preserved as a config key.  See 'fetch' for a description
@@ -986,7 +994,8 @@ placed at refs/remotes/origin/* rather than the default refs/remotes/*.
 The former is more compatible with the layout of Git's "regular"
 remote-tracking refs (refs/remotes/$remote/*), and may potentially
 prevent similarly named SVN branches and Git remotes from clobbering
-each other.
+each other. In Git v2.0 the default prefix used (i.e. when no --prefix
+is given) will change from "" (no prefix) to "origin/".
 
 When using multiple --branches or --tags, 'git svn' does not automatically
 handle name collisions (for example, if two branches from different paths have
diff --git a/git-svn.perl b/git-svn.perl
index ff1ce3d..0443a4f 100755
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -1389,7 +1389,17 @@ sub cmd_multi_init {
 		usage(1);
 	}
 
-	$_prefix = '' unless defined $_prefix;
+	unless (defined $_prefix) {
+		$_prefix = '';
+		warn <<EOF
+WARNING: --prefix is not given, defaulting to empty prefix.
+         This is probably not what you want! In order to stay compatible
+         with regular remote-tracking refs, provide a prefix like
+         --prefix=origin/ (remember the trailing slash), which will cause
+         the SVN-tracking refs to be placed at refs/remotes/origin/*.
+NOTE: In Git v2.0, the default prefix will change from empty to 'origin/'.
+EOF
+	}
 	if (defined $url) {
 		$url = canonicalize_url($url);
 		init_subdir(@_);
diff --git a/t/t9117-git-svn-init-clone.sh b/t/t9117-git-svn-init-clone.sh
index b7ef9e2..69e9c0d 100755
--- a/t/t9117-git-svn-init-clone.sh
+++ b/t/t9117-git-svn-init-clone.sh
@@ -52,4 +52,71 @@ test_expect_success 'clone to target directory with --stdlayout' '
 	rm -rf target
 	'
 
+test_expect_success 'init without -s/-T/-b/-t does not warn' '
+	test ! -d trunk &&
+	git svn init "$svnrepo"/project/trunk trunk 2>warning &&
+	test_must_fail grep -q prefix warning &&
+	rm -rf trunk &&
+	rm -f warning
+	'
+
+test_expect_success 'clone without -s/-T/-b/-t does not warn' '
+	test ! -d trunk &&
+	git svn clone "$svnrepo"/project/trunk 2>warning &&
+	test_must_fail grep -q prefix warning &&
+	rm -rf trunk &&
+	rm -f warning
+	'
+
+test_svn_configured_prefix () {
+	prefix=$1 &&
+	cat >expect <<EOF &&
+project/trunk:refs/remotes/${prefix}trunk
+project/branches/*:refs/remotes/${prefix}*
+project/tags/*:refs/remotes/${prefix}tags/*
+EOF
+	test ! -f actual &&
+	git --git-dir=project/.git config svn-remote.svn.fetch >>actual &&
+	git --git-dir=project/.git config svn-remote.svn.branches >>actual &&
+	git --git-dir=project/.git config svn-remote.svn.tags >>actual &&
+	test_cmp expect actual &&
+	rm -f expect actual
+}
+
+test_expect_success 'init with -s/-T/-b/-t without --prefix warns' '
+	test ! -d project &&
+	git svn init -s "$svnrepo"/project project 2>warning &&
+	grep -q prefix warning &&
+	test_svn_configured_prefix "" &&
+	rm -rf project &&
+	rm -f warning
+	'
+
+test_expect_success 'clone with -s/-T/-b/-t without --prefix warns' '
+	test ! -d project &&
+	git svn clone -s "$svnrepo"/project 2>warning &&
+	grep -q prefix warning &&
+	test_svn_configured_prefix "" &&
+	rm -rf project &&
+	rm -f warning
+	'
+
+test_expect_success 'init with -s/-T/-b/-t and --prefix does not warn' '
+	test ! -d project &&
+	git svn init -s "$svnrepo"/project project --prefix="" 2>warning &&
+	test_must_fail grep -q prefix warning &&
+	test_svn_configured_prefix "" &&
+	rm -rf project &&
+	rm -f warning
+	'
+
+test_expect_success 'clone with -s/-T/-b/-t and --prefix does not warn' '
+	test ! -d project &&
+	git svn clone -s "$svnrepo"/project --prefix="" 2>warning &&
+	test_must_fail grep -q prefix warning &&
+	test_svn_configured_prefix "" &&
+	rm -rf project &&
+	rm -f warning
+	'
+
 test_done
-- 
1.8.4.653.g2df02b3