D7258: makefile: use python3 by default (BC)

[durin42 (Augie Fackler)]

durin42 added a comment.


  In D7258#106949 <https://phab.mercurial-scm.org/D7258#106949>, @mharbison72 wrote:
  
  > This will break Windows by default, because py3 is still named `python.exe`.  Alternately, I've been using using `PYTHON="py -3"` to invoke `make`.
  
  I'm not sure what we should do here. We probably can't change the default only for Windows somehow? (My make-fu is not awesome)
  
  > The command issued to the buildbot will need to explicitly use `PYTHON="py -2"` to keep that happy.  Probably also need to invoke `run-tests.py` with the right python too, so that `$PYTHON` is correct.  It looks like the shebang lines are already `$PYTHON`, through some aren't quoted.
  
  Okay, I'll see about wiring that up tonight or tomorrow then. I believe that's the only (other) thing blocking this?
  
  > CC @durin42

REPOSITORY
  rHG Mercurial

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  https://phab.mercurial-scm.org/D7258/new/

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

To: indygreg, #hg-reviewers, martinvonz
Cc: mharbison72, durin42, dlax, martinvonz, mercurial-devel