[gentoo-python] Cython warnings with PyPy 6.0.0

[Michał Górny]

Hi,

Apparently PyPy 6.0.0 fixed a bug in type sizes which Cython up
to 0.28.2 worked around.  As a result, .pyx files generated with older
versions of Cython will spew (harmless) warnings:

>>>> import numpy
/data/extra/pypy/6.0.0/site-packages/numpy/random/__init__.py:99: UserWarning: __builtin__.type size changed, may indicate binary incompatibility. Expected 888, got 408
  from .mtrand import *

Apparently upgrading Cython locally is not enough to fix it, since
packages frequently include pregenerated files and we usually don't
regenerate them.

To be honest, I don't think this is something we need to solve.  We can
just wait for upstreams to upgrade Cython and generate new packages.

Alternatively, we can remove the generated files from unpacked sources
to force setup.py to regenerate them.  I've seen some packages doing
that.  It may be in the 'Gentoo spirit' but I don't have a strong
opinion with that kind of files.

Finally, upstream provides a .pth hack that silences the warning. 
However, I'd rather not do add more hacks to the stack.

Source: https://morepypy.blogspot.com/2018/04/how-to-ignore-annoying-cython-warnings.html

-- 
Best regards,
Michał Górny