[Buildroot] [PATCH 1/1] python3: add patch to fix PEP 3147 issue with automake built packages

[Christophe Vu-Brugier <cvubrugier@fastmail.fm>]

Hi Thomas,

On Fri, 28 Aug 2015 19:36:43 +0200, Thomas Petazzoni wrote :
> On Fri, 28 Aug 2015 16:58:41 +0200, Christophe Vu-Brugier wrote:
> > Packages built with automake use a `py-compile` helper to
> > byte-compile Python source files. This script uses the "py_compile"
> > module from the standard library. In turn, the compile() function
> > in the "py_compile" module invokes the cache_from_source() function
> > provided by importlib.
> > 
> > This patch changes cache_from_source() and source_from_cache() in
> > importlib to get rid of the "__pycache__" directory.
> > 
> > This fixes the following import error in kmod when the module is
> > built for Python 3:
> > 
> >   >>> from kmod import Kmod
> >   Traceback (most recent call last):
> >     File "<stdin>", line 1, in <module>
> >   ImportError: cannot import name 'Kmod'
> > 
> > Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>
> 
> Thanks for this patch. However, I'm wondering if it doesn't make the
> existing patch 016-distutils-no-pep3147.patch unnecessary. Patch 016
> fixes the distutils/setuptools case by preventing the logic from
> calling importlib.util.cache_from_source(). But since you're fixing
> this function in your patch, maybe there's no need for the 016 patch
> anymore ? What about patch 004 ?
> 
> Could you do some quick testing without patches 004 and 016, and see
> if 1/ the Python standard library is byte-compiled without __pycache__
> folders and 2/ same for Python external modules built with distutils
> and setuptools.
> 
> I'm pretty sure with your patch we can remove patch 016 (so your patch
> could replace it). I'm not sure about patch 004, though.

Indeed, patch 016 for distutils / setuptools is no longer necessary.
Moreover, patch 004 for the standard library can be dropped as well.
Afer removing patches 004 and 016, I see no __pycache__ directory in the
Python path and the interpreter behaves as expected (I tested by loading
modules and running samples for readline, urwid, six, kmod or
pyparsing).

I will respin my patch to drop 004 and 016 and update 005 which is
impacted by the removal of 004.

Thank you !

-- 
Christophe Vu-Brugier