diff -r ec222a29bdf0 -r 94b200a11cf7 mercurial/util.py
--- a/mercurial/util.py	Tue Sep 13 17:01:07 2011 -0500
+++ b/mercurial/util.py	Wed Sep 21 22:52:00 2011 +0200
@@ -24,6 +24,10 @@
 def sha1(s):
     return _fastsha1(s)
 
+_notset = object()
+def safehasattr(thing, attr):
+    return getattr(thing, attr, _notset) is not _notset
+
 def _fastsha1(s):
     # This function will import sha1 from hashlib or sha (whichever is
     # available) and overwrite itself with it on the first call.