git filter-branch doesn't dereference annotated tags

From: Grégory Pakosz <gpakosz@visionobjects.com>
Date: Dec 31, 2012, 16:24 UTC
Message-ID: <CAC_01E174m_6tDwPKZ5P0BUxnLNWUf9p+VkECFosPTzip0sYsA@mail.gmail.com>

Please disregard the previous email that contains an incorrect fix suggestion. I wish my first contribution was flawless.

Here is what's happening. git-filter-branch let git-update-ref -d verify that the value for $ref matches $sha1. However, when $ref points to an annotated tag that is being deleted, that verification fails because $sha1 is the commit underneath.

I think there are two possible fixes:
  1) either make git-filter-branch dereference annotated tags and do
the verification itself then use the two arguments version of git
update-ref
  2) in the case of an annotated tag, pass another <old value> to git update-ref

Please find below a patch that implements solution 1). Please note the patch doesn't contain a unit test for this situation as I wasn't sure how to provide one. Yet I tested it on the repository I'm working on.

Gregory

>From 9d21960088a61bfbac1ffdb4b13e3038f88ab4d6 Mon Sep 17 00:00:00 2001

From: Gregory Pakosz <gpakosz@visionobjects.com>
Date: Mon, 31 Dec 2012 15:30:36 +0100
Subject: [PATCH] git-filter-branch: support annotated tags deletion

git-filter-branch let git-update-ref -d verify that the value for $ref matches $sha1. However, when $ref is an annotated tag being deleted that verfication fails because $sha1 corresponds to a commit object.

Instead of asking git-update-ref to verify values actually match, dereference $ref ourselves and test against $sha1 first. Then invoke git-update-ref with two arguments.

Signed-off-by: Gregory Pakosz <gpakosz@visionobjects.com>
---
 git-filter-branch.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 5314249..bbee6d0 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -383,7 +383,7 @@ do
 	case "$rewritten" in
 	'')
 		echo "Ref '$ref' was deleted"
-		git update-ref -m "filter-branch: delete" -d "$ref" $sha1 ||
+		test $(git rev-parse --verify "$ref^{commit}") = $sha1 && git
update-ref -m "filter-branch: delete" -d "$ref" ||
 			die "Could not delete $ref"
 	;;
 	$_x40)

-- 
1.8.0.1

From 9d21960088a61bfbac1ffdb4b13e3038f88ab4d6 Mon Sep 17 00:00:00 2001
From: Gregory Pakosz <gpakosz@visionobjects.com>
Date: Mon, 31 Dec 2012 15:30:36 +0100
Subject: [PATCH] git-filter-branch: support annotated tags deletion

git-filter-branch let git-update-ref -d verify that the value for $ref matches
$sha1. However, when $ref is an annotated tag being deleted that verfication
fails because $sha1 corresponds to a commit object.

Instead of asking git-update-ref to verify values actually match, dereference
$ref ourselves and test against $sha1 first. Then invoke git-update-ref with two
arguments.

Signed-off-by: Gregory Pakosz <gpakosz@visionobjects.com>
---
 git-filter-branch.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/git-filter-branch.sh b/git-filter-branch.sh
index 5314249..bbee6d0 100755
--- a/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@ -383,7 +383,7 @@ do
 	case "$rewritten" in
 	'')
 		echo "Ref '$ref' was deleted"
-		git update-ref -m "filter-branch: delete" -d "$ref" $sha1 ||
+		test $(git rev-parse --verify "$ref^{commit}") = $sha1 && git update-ref -m "filter-branch: delete" -d "$ref" ||
 			die "Could not delete $ref"
 	;;
 	$_x40)
-- 
1.8.0.1