py3: use range instead of xrange in tests/test-
issue4074.t
xrange in not present on Python 3.
Differential Revision: https://phab.mercurial-scm.org/D2329
py3: use range instead of xrange in tests/test-convert-mtn.t
xrange in not present on Python 3.
This change will make the test a bit slower on Python 2.
Differential Revision: https://phab.mercurial-scm.org/D2328