diff -r 6c0be67c2b27 -r 3be4785f8994 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Wed Mar 14 18:49:10 2007 -0500
+++ b/mercurial/localrepo.py	Wed Mar 14 19:13:04 2007 -0500
@@ -328,7 +328,8 @@
         self.tagscache = {}
         for k,nh in globaltags.items():
             n = nh[0]
-            self.tagscache[k] = n
+            if n != nullid:
+                self.tagscache[k] = n
         self.tagscache['tip'] = self.changelog.tip()
 
         return self.tagscache