--- a/mercurial/manifest.py	Wed Mar 18 12:03:44 2015 -0500
+++ b/mercurial/manifest.py	Wed Mar 18 13:37:18 2015 -0500
@@ -164,7 +164,7 @@
             return self.copy()
 
         files = match.files()
-        if (match.matchfn == match.exact or
+        if ((match.matchfn == match.exact and len(files) < 100) or
             (not match.anypats() and util.all(fn in self for fn in files))):
             return self.intersectfiles(files)