--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -307,7 +307,7 @@ class localrepository(repo.repository):
if bn != an and an in bh and \
(bn not in ah or len(bh) > len(ah)):
an = bn
- ah.append([n for n in bh if n not in ah])
+ ah.extend([n for n in bh if n not in ah])
globaltags[k] = an, ah
# read the tags file from each head, ending with the tip
--- a/tests/test-tags
+++ b/tests/test-tags
@@ -104,4 +104,21 @@ hg ci -m 'change foo' -d '1000000 0'
hg tags
hg tag -d '1000000 0' -r 3 bar # should complain
-hg tags
\ No newline at end of file
+hg tags
+
+# test tag rank with 3 heads
+cd ..
+hg init t4
+cd t4
+echo foo > foo
+hg add
+hg ci -m 'add foo' -d '0 0' # rev 0
+hg tag -d '0 0' bar # rev 1 bar -> 0
+hg tag -d '0 0' -f bar # rev 2 bar -> 1
+hg up -qC 0
+hg tag -d '0 0' -fr 2 bar # rev 3 bar -> 2
+hg tags
+hg up -qC 0
+hg tag -d '0 0' -m 'retag rev 0' -fr 0 bar # rev 4 bar -> 0, but bar stays at 2
+echo % bar should still point to rev 2
+hg tags
--- a/tests/test-tags.out
+++ b/tests/test-tags.out
@@ -57,3 +57,9 @@ bar 0:b40
abort: a tag named bar already exists (use -f to force)
tip 6:b5ff9d142648
bar 0:b409d9da318e
+adding foo
+tip 3:ca8479b4351c
+bar 2:72b852876a42
+% bar should still point to rev 2
+tip 4:40af5d225513
+bar 2:72b852876a42