[REVISED PATCH] filter-branch: rewrite only unexcluded refs

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

The rev-list options can exclude some -- or all -- refs:

	git filter-branch <some-filter> master ^master

Without this patch, these refs are assumed to be deleted, or worse, they
are rewritten to some bogus merge bases.

So really exclude excluded refs from being rewritten.  This also allows
you to safely call

	git filter-branch <some-filter> --all <rev-list options>

to rewrite _all_ branches and tags.

Thanks go to Johannes Sixt for help on the implementation and for testing.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 git-filter-branch.sh     |   16 +++++++++++++++-
 t/t7003-filter-branch.sh |    9 +++++++++
 2 files changed, 24 insertions(+), 1 deletions(-)

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 4fb3abe..3fa2f63 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -181,6 +181,14 @@ export GIT_DIR GIT_WORK_TREE=.
 
 # These refs should be updated if their heads were rewritten
 
+negatives="`git rev-parse "$@" | while read line
+	do
+		case "$line" in
+		$_x40) ;;
+		*) echo "$line";;
+		esac
+	done`"
+
 git rev-parse --revs-only --symbolic "$@" |
 while read ref
 do
@@ -196,7 +204,13 @@ do
 			grep -e "^refs/heads/$ref$" -e "^refs/tags/$ref$")"
 	esac
 
-	git check-ref-format "$ref" && echo "$ref"
+	# make sure we have a valid ref
+	git check-ref-format "$ref" || continue
+
+	# if the ref has been excluded by the other options, skip it
+	test -z "$(git rev-list -1 "$ref" $negatives --topo-order)" && continue
+
+	echo "$ref"
 done > "$tempdir"/heads
 
 test -s "$tempdir"/heads ||
diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index c9a820d..667eda7 100755
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -164,4 +164,13 @@ test_expect_success 'only dwim refs/heads/$ref or refs/tags/$ref' '
 	git filter-branch -f master
 '
 
+test_expect_success 'do not update uninteresting refs' '
+	branch=$(git rev-parse branch) &&
+	master=$(git rev-parse master) &&
+	git filter-branch -f --env-filter "GIT_AUTHOR_EMAIL=xy@probl.em" \
+		master ^removed-author branch &&
+	test $branch = $(git rev-parse branch) &&
+	test $master != $(git rev-parse master)
+'
+
 test_done
-- 
1.5.3.rc2.32.g35c5b-dirty