diff -r b79cdb7f0597 -r 22ebd6ee5672 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Sun Jun 03 14:38:52 2007 -0300
+++ b/mercurial/localrepo.py	Mon Jun 04 00:26:53 2007 -0300
@@ -303,7 +303,7 @@
                 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