BUG: git filter-branch does not make tree replacements permanent

From

Robert Luberda <robert@debian.org>

Date

Apr 11, 2013, 21:08 UTC

Message-ID

<20130411210816.GA15810@vox.robbo.home>

Hi,

The git filter-branch man page states:

  NOTE: This command honors .git/info/grafts and .git/refs/replace/. 
        If you have any grafts or replacement refs defined, running 
        this command will make them permanent.

1. Setup:
	git init
	for i in a b c d; do echo $i >> f; git add f; git commit -m "$i"; done
	git diff HEAD~2..HEAD~1  # the output is non-empty
2. Add replacement for some tree object
	git replace `git log --format=raw | sed -ne 's/^tree //p' | sed -n 2,3p | tac`
	git diff HEAD~2..HEAD~1  # the output is now empty
3. Run filter-branch:
	git filter-branch
4. Verify that unfortunatelly it did nothing:
	git replace | xargs git replace -d
	git diff HEAD~2..HEAD~1  # the output is still not empty

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index ac2a005..68064f2 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -276,6 +276,16 @@ test $commits -eq 0 && die "Found nothing to rewrite"
 
 # Rewrite the commits
 
+write_tree_func()
+{
+ m="$(git write-tree "$@")"
+ if [ -e "$ORIG_GIT_DIR/refs/replace/$m" ] ; then
+   n="$(cat "$ORIG_GIT_DIR/refs/replace/$m")"
+   echo "Replaced tree $m with $n" >&2
+   m="$n"
+ fi
+ echo "$m"
+}
 git_filter_branch__commit_count=0
 while read commit parents; do
 	git_filter_branch__commit_count=$(($git_filter_branch__commit_count+1))
@@ -342,8 +352,8 @@ while read commit parents; do
 	sed -e '1,/^$/d' <../commit | \
 		eval "$filter_msg" > ../message ||
 			die "msg filter failed: $filter_msg"
-	workdir=$workdir @SHELL_PATH@ -c "$filter_commit" "git commit-tree" \
-		$(git write-tree) $parentstr < ../message > ../map/$commit ||
+	workdir=$workdir /bin/sh -c "$filter_commit" "git commit-tree" \
+		$(write_tree_func) $parentstr < ../message > ../map/$commit ||
 			die "could not write rewritten commit"
 done <../revs

Regards,
robert