tests: fix PYTHONPATH manipulation on Windows Without the semicolon separator and quotes, the variables ends up like this: c:\Users\Matt\projects\hg-evolve:c:\Users\Matt\projects\hg-evolve: c:\Users\Matt\projects\hg;c:\Users\Matt\projects\hg-evolve\tests; c:\Users\Matt\projects\hg\tests That in turn makes the local evolve code unreachable, and the system installed code is tested instead. I'm testing against `uname` instead of a trivial python script printing os.name because maybe one day tests will run on WSL.

#require test-repo pyflakes

Copied from Mercurial core (60ee2593a270)

  $ cd "`dirname "$TESTDIR"`"

run pyflakes on all tracked files ending in .py or without a file ending
(skipping binary file random-seed)

  $ hg locate 'set:(**.py or grep("^#!.*python")) - removed()' 2>/dev/null \
  > | xargs pyflakes 2>/dev/null