diff tests/hghave.py @ 39351:4cfd1eebe6aa

hghave: move from requiring the PYTHON3 env var to looking for `python3`

We're starting to write new utility scripts in Python 3, and I think
it's reasonable to expect `python3` to be something we should use if
it's present. I wrote the regex to specifically ban Python 3 prior to
Python 3.5 because we won't ever support that.

I moved the only test that was using $PYTHON3 to just using `python3`
directly.

Differential Revision: https://phab.mercurial-scm.org/D4290

--- a/tests/hghave.py	Wed Aug 29 09:59:08 2018 -0700
+++ b/tests/hghave.py	Wed Jul 25 13:45:28 2018 -0400
@@ -631,7 +631,7 @@
 
 @check("py3exe", "a Python 3.x interpreter is available")
 def has_python3exe():
-    return 'PYTHON3' in os.environ
+    return matchoutput('python3 -V', br'^Python 3.(5|6|7|8|9)')
 
 @check("py3pygments", "Pygments available on Python 3.x")
 def has_py3pygments():