Seems like my message did not go through:

This change will not solve out problem!

PEP 552 proposes a new file-format for .pyc file and a hash-based
mechanism for checking if the .pyc file is recent. This means, you can
not backport this changes to Python 3.6 or older. Even if you manage to
backport, this would seriously break all tools working on .pyc files.

We only support Python 2 and the latest (in Guix, anyway!) Python 3
interpreter.  So while we will indeed need a solution for Python2, we
don't have to care about older 3.x variants.

This depends on what you call "older 3.5 variants". :-)

The current version is Python 3.6. Guix has 3.5 (and 2.7).

Python 3.7 (which will materialize PEP 552 ) is planed for mid of 2018.

-- 
Regards
Hartmut Goebel

| Hartmut Goebel          | h.goebel@crazy-compilers.com               |
| www.crazy-compilers.com | compilers which you thought are impossible |