--- a/mercurial/match.py	Tue Jun 06 11:16:38 2017 -0400
+++ b/mercurial/match.py	Thu Jun 08 22:18:17 2017 -0700
@@ -85,7 +85,7 @@
             return False
     return True
 
-def match(root, cwd, patterns, include=None, exclude=None, default='glob',
+def match(root, cwd, patterns=None, include=None, exclude=None, default='glob',
           exact=False, auditor=None, ctx=None, listsubrepos=False, warn=None,
           badfn=None, icasefs=False):
     """build an object to match a set of file patterns