[PATCH v6 p1.1 14/14] fast-export: make sure updated refs get updated

[Felipe Contreras <felipe.contreras@gmail.com>]

When an object has already been exported (and thus is in the marks) it's
flagged as SHOWN, so it will not be exported again, even if in a later
time it's exported through a different ref.

We don't need the object to be exported again, but we want the ref
updated, which doesn't happen.

Since we can't know if a ref was exported or not, let's just assume that
if the commit was marked (flags & SHOWN), the user still wants the ref
updated.

IOW: If it's specified in the command line, it will get updated,
regardless of whether or not the object was marked.

So:

 % git branch test master
 % git fast-export $mark_flags master
 % git fast-export $mark_flags test

Would export 'test' properly.

Additionally, this fixes issues with remote helpers; now they can push
refs whose objects have already been exported, and a few other issues as
well. Update the tests accordingly.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
---
 builtin/fast-export.c     | 10 +++++++---
 t/t5801-remote-helpers.sh | 20 ++++++++------------
 t/t9350-fast-export.sh    | 15 +++++++++++++++
 3 files changed, 30 insertions(+), 15 deletions(-)

diff --git a/builtin/fast-export.c b/builtin/fast-export.c
index 191936c..31bfbee 100644
--- a/builtin/fast-export.c
+++ b/builtin/fast-export.c
@@ -523,10 +523,14 @@ static void get_tags_and_duplicates(struct object_array *pending,
 				typename(e->item->type));
 			continue;
 		}
-		if (commit->util)
-			/* more than one name for the same object */
+
+		/*
+		 * This ref will not be updated through a commit, lets make
+		 * sure it gets properly updated eventually.
+		 */
+		if (commit->util || commit->object.flags & SHOWN)
 			string_list_append(extra_refs, full_name)->util = commit;
-		else
+		if (!commit->util)
 			commit->util = full_name;
 	}
 }
diff --git a/t/t5801-remote-helpers.sh b/t/t5801-remote-helpers.sh
index 12ae256..b2782a2 100755
--- a/t/t5801-remote-helpers.sh
+++ b/t/t5801-remote-helpers.sh
@@ -63,18 +63,6 @@ test_expect_success 'fetch new branch' '
 	compare_refs server HEAD local FETCH_HEAD
 '
 
-#
-# This is only needed because of a bug not detected by this script. It will be
-# fixed shortly, but for now lets not cause regressions.
-#
-test_expect_success 'bump commit in server' '
-	(cd server &&
-	git checkout master &&
-	echo content >>file &&
-	git commit -a -m four) &&
-	compare_refs server HEAD server HEAD
-'
-
 test_expect_success 'fetch multiple branches' '
 	(cd local &&
 	 git fetch
@@ -162,4 +150,12 @@ test_expect_failure 'pushing without marks' '
 	compare_refs local2 HEAD server HEAD
 '
 
+test_expect_success 'push ref with existing object' '
+	(cd local &&
+	git branch dup master &&
+	git push origin dup
+	) &&
+	compare_refs local dup server dup
+'
+
 test_done
diff --git a/t/t9350-fast-export.sh b/t/t9350-fast-export.sh
index 1f59862..237d2e5 100755
--- a/t/t9350-fast-export.sh
+++ b/t/t9350-fast-export.sh
@@ -454,4 +454,19 @@ test_expect_success 'test bidirectionality' '
 	git fast-import --export-marks=marks-cur --import-marks=marks-cur
 '
 
+cat > expected << EOF
+reset refs/heads/master
+from :12
+
+EOF
+
+test_expect_success 'refs are updated even if no commits need to be exported' '
+	> tmp-marks &&
+	git fast-export --import-marks=tmp-marks \
+		--export-marks=tmp-marks master > /dev/null &&
+	git fast-export --import-marks=tmp-marks \
+		--export-marks=tmp-marks master > actual &&
+	test_cmp expected actual
+'
+
 test_done
-- 
1.8.0