python2: backport fix for pyc race condition

[timokau]

Motivation for this change

This is python bug https://bugs.python.org/issue13146. Fixed since
python 3.4. It makes pyc creation atomic, preventing a race condition.
The patch has been rebased on our deterministic build patch.

It wasn't backported to python 2.7 because there was a complaint about
changed semantics. Since files are now created in a temporary directory
and then moved, symlinks will be overridden. See
https://bugs.python.org/issue17222.

That is an edge-case however. Ubuntu and debian have backported the fix
in 2013 already, making it mainstream enough for us to adopt.

CC @FRidh. I became aware of this bug while trying to build the py2 version of tensorflow from source with 12 build cores (#63616). I have also seen transient test failures for sage on hydra several times that may have been caused by this bug.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

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