py3: open file in rb mode

mercurial/match.py

@@ -742,7 +742,7 b' def readpatternfile(filepath, warn, sour'
     syntax = 'relre:'
     patterns = []
 
-    fp = open(filepath)
+    fp = open(filepath, 'rb')
     for lineno, line in enumerate(util.iterfile(fp), start=1):
         if "#" in line:
             global _commentre