Marc Chevrier authored Aug 04, 2020 and Brad King committed Aug 07, 2020

Do not set the policy version before recording our internal macros such
as `__Python_add_library`.  Otherwise callers get our policy version
instead of theirs.  Instead just set the specific policies we need.

Also fix one case in our test suite where we were accidentally
relying on the policy version to be set by `FindPython`.

Fixes: #21042