diff -r 7f7425306925 -r 3b4e00cba57a mercurial/localrepo.py
--- a/mercurial/localrepo.py	Sat Oct 28 23:37:59 2006 -0300
+++ b/mercurial/localrepo.py	Sun Oct 29 10:53:51 2006 +0100
@@ -332,10 +332,10 @@
                     node, label = l.rstrip().split(" ", 1)
                     partial[label] = bin(node)
             else: # invalidate the cache
-                last, lrev = nullid, -1
+                last, lrev = nullid, nullrev
             f.close()
         except IOError:
-            last, lrev = nullid, -1
+            last, lrev = nullid, nullrev
         return partial, last, lrev
 
     def _writebranchcache(self, branches, tip, tiprev):