bug#24557: python importer: extend requirements import

[Danny Milosavljevic <dannym@scratchpost.org>]

On Wed, 28 Sep 2016 16:35:26 +0000
ng0 <ngillmann@runbox.com> wrote:

> One example:
> 
> ng0@shadowwalker ~$ guix import pypi hyperkitty
> 
> Starting download of /tmp/guix-file.yrqmcv
> >From https://pypi.python.org/packages/47/2d/cc2adf4bc0ed7bb4189b3146dde921c9a6ecc33f0f87c96c744d89bab154/HyperKitty-1.0.3.tar.gz...  
>  …1.0.3.tar.gz  1.5MiB              1.1MiB/s 00:01 [####################] 100.0%
> tar: HyperKitty-1.0.3/requirements.txt: Not found in archive
> tar: Exiting with failure status due to previous errors
> guix import: warning: 'tar xf' failed with exit code 512
> (package
>   (name "python-hyperkitty")
>   (version "1.0.3")
> 
> 
> When you look at the contained setup.py of hyperkitty, it has this
> defined in setup.py.
> 
> # Requirements REQUIRES = [
> etc etc
> 
> I've seen this in some variations.
> 
> The python importer should be extended to include these not very unusual
> cases.

This could be done by making the Python importer do something like

  hk/HyperKitty-1.0.3 $ python3 setup.py egg_info
  hk/HyperKitty-1.0.3 $ cat HyperKitty.egg-info/requires.txt 

if (!) the project uses setuptools.

(Unfortunately there seems to be no command line option to directly read the keyword argument "install_requires" by setup.py - although there are command line options for all the other keyword arguments - weird... That's why it's necessary to make it write them egg_info files)