py3: use '//' for integer divisions

py3: use '//' for integer divisions

Differential Revision: https://phab.mercurial-scm.org/D2413

--- a/tests/test-mq-missingfiles.t	Sat Feb 24 01:21:22 2018 +0530
+++ b/tests/test-mq-missingfiles.t	Sat Feb 24 01:22:15 2018 +0530
@@ -10,7 +10,7 @@
   > assert (len(args) % 2) == 0
   > 
   > f = open(path, 'wb')
-  > for i in range(len(args)/2):
+  > for i in range(len(args) // 2):
   >    count, s = args[2*i:2*i+2]
   >    count = int(count)
   >    s = s.decode('string_escape')