diff -r 1e701ffd9df4 -r 5116a077c3da mercurial/localrepo.py
--- a/mercurial/localrepo.py	Sat May 29 20:32:39 2010 +0200
+++ b/mercurial/localrepo.py	Thu May 27 17:47:40 2010 +0200
@@ -971,7 +971,8 @@
                 self.branchtags()
             return n
         finally:
-            del tr
+            if tr:
+                tr.release()
             lock.release()
 
     def destroyed(self):
@@ -2194,7 +2195,7 @@
 
             tr.close()
         finally:
-            del tr
+            tr.release()
 
         if changesets > 0:
             # forcefully update the on-disk branch cache