--- a/mercurial/cmdutil.py	Sat Apr 08 11:02:37 2017 +0530
+++ b/mercurial/cmdutil.py	Fri May 05 01:26:13 2017 +0530
@@ -491,10 +491,10 @@
         patlen = len(pat)
         i = 0
         while i < patlen:
-            c = pat[i]
+            c = pat[i:i + 1]
             if c == '%':
                 i += 1
-                c = pat[i]
+                c = pat[i:i + 1]
                 c = expander[c]()
             newname.append(c)
             i += 1