diff -r 83968ae4aaf2 -r 502474839293 mercurial/merge.py
--- a/mercurial/merge.py	Tue May 04 15:52:42 2010 -0500
+++ b/mercurial/merge.py	Wed May 05 20:21:57 2010 -0500
@@ -491,6 +491,7 @@
 
         ### calculate phase
         action = []
+        wc.status(unknown=True) # prime cache
         if not force:
             _checkunknown(wc, p2)
         if not util.checkcase(repo.path):