tests/test-gendoc-zh_CN.t

diffstat: make --git work properly on renames (issue6025)

`$ hg diff --stat --git` shows only the new filename on renames.
I added the old filename also to the output to make it identical
with the output of `$ git diff --stat`.

Differential Revision: https://phab.mercurial-scm.org/D5628

#require docutils gettext

  $ $TESTDIR/check-gendoc zh_CN
  checking for parse errors