diff -r c94c1aeb35fb -r 3e8eb6d84a5c mercurial/context.py
--- a/mercurial/context.py	Tue Jun 06 11:16:38 2017 -0400
+++ b/mercurial/context.py	Thu Jun 08 22:18:17 2017 -0700
@@ -301,8 +301,6 @@
 
     def match(self, pats=None, include=None, exclude=None, default='glob',
               listsubrepos=False, badfn=None):
-        if pats is None:
-            pats = []
         r = self._repo
         return matchmod.match(r.root, r.getcwd(), pats,
                               include, exclude, default,
@@ -1701,8 +1699,6 @@
 
     def match(self, pats=None, include=None, exclude=None, default='glob',
               listsubrepos=False, badfn=None):
-        if pats is None:
-            pats = []
         r = self._repo
 
         # Only a case insensitive filesystem needs magic to translate user input