py3: use range instead of xrange in tests/test-mq-qimport.t

py3: use range instead of xrange in tests/test-mq-qimport.t

xrange is not present on Python 3.

Differential Revision: https://phab.mercurial-scm.org/D2330

--- a/tests/test-mq-qimport.t	Sun Feb 18 18:19:10 2018 +0530
+++ b/tests/test-mq-qimport.t	Sun Feb 18 18:20:21 2018 +0530
@@ -7,7 +7,7 @@
   > assert (len(args) % 2) == 0
   > 
   > f = open(path, 'wb')
-  > for i in xrange(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')