D5079: py3: use py3 as the test tag, dropping the k

[mjpieters (Martijn Pieters)]

mjpieters added a comment.


  Note: I undid the change to `mercurial/thirdparty/zope/interface/_compat.py` as it should not have been changed to begin with.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D5079

To: mjpieters, #hg-reviewers, pulkit, durin42
Cc: durin42, pulkit, mercurial-devel