tests/test-gendoc-zh_TW.t

py3: add test-contrib-emacs.t to passing tests list

I installed emacs on the server running buildbot and the test started passing on
Python 3. Lets add it to the list of passing test.

Differential Revision: https://phab.mercurial-scm.org/D6500

#require docutils gettext

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