[Ohrrpgce] SVN: teeemcee/12602 scons: explicitly invoke python3, overridable with python= arg or PYTHON

[subversion at HamsterRepublic.com]

teeemcee
2021-10-30 17:56:36 -0700 (Sat, 30 Oct 2021)
195
scons: explicitly invoke python3, overridable with python= arg or PYTHON envvar

Using #! lines on Windows may not be reliable, and also sometimes you need to specify
a particular python version.
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U   wip/SConscript