D7258: makefile: use python3 by default (BC)

[indygreg (Gregory Szorc)]

indygreg added a comment.


  In D7258#106380 <https://phab.mercurial-scm.org/D7258#106380>, @martinvonz wrote:
  
  > All tests except for `test-check-py3-compat.t` pass on py3 (on Linux), right?
  
  Yes, tests are clean on Python 3.6 and 3.7. See https://ci.hg.gregoryszorc.com/.

REPOSITORY
  rHG Mercurial

CHANGES SINCE LAST ACTION
  https://phab.mercurial-scm.org/D7258/new/

REVISION DETAIL
  https://phab.mercurial-scm.org/D7258

To: indygreg, #hg-reviewers, martinvonz
Cc: dlax, martinvonz, mercurial-devel