Mailman 2.1: hardcoded site-packages dir prefix doesn't work on some 64 bit filesystem layouts

[Hanno Böck]

Mailman's paths.py.in contains code to add the python site-packages dir to the path. This uses a hardcoded "lib" prefix:

 # Include Python's site-packages directory.
sitedir = os.path.join(sys.prefix, 'lib', 'python'+sys.version[:3],
                       'site-packages')
sys.path.append(sitedir)

On 64 bit systems this is usually lib64 and some distros started removing the compatibility symlink lib->lib64 and split up lib and lib64 (e.g. latest Gentoo profiles). So relying on "lib" as a prefix is not compatible any more.

Python has a function getsitepackages in the site module and I believe it's best to rely on python knowing best where its directories are. It returns an array, so this would look like this:
sitedirs = site.getsitepackages()
for sitedir in sitedirs:
    sys.path.append(sitedir)

Patch attached, please apply.

[Mark Sapiro (msapiro)]

I appreciate the patch. Thank you.

One issue is that site.getsitepackages() requires Python 2.7. It is probably time to stop supporting older versions anyway, so this shouldn't be a problem.

[Mark Sapiro (msapiro)]

I have now looked at the code for site.getsitepackages() at https://github.com/python/cpython/blob/master/Lib/site.py#L319 and it seems no better than what's in paths.py.in, so I'm not sure this will be effective unless your distro hacks site.py. Is that the case?

It appears Ubuntu does hack site.getsitepackages() to actually return ['/usr/local/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages'].

I am reluctant to do anything without a better understanding of what site.getsitepackages() returns in various distros.

[Hanno Böck (hanno-hboeck)]

I'm on Gentoo, seems it also patches the site.py accordingly:

https://gitweb.gentoo.org/repo/gentoo.git/tree/dev-lang/python/python-2.7.16.ebuild#n106

[Robie Basak (racb)]

Please could someone confirm if this actually requires patching in Ubuntu? I'm not aware that Ubuntu uses "lib64", and "/usr/local" isn't used by system-provided packages anyway. What is the use case that fails in Ubuntu?

Once answered please change the Ubuntu bug task status accordingly (Invalid or New depending on the answer I guess).

[Paul White (paulw2u)]

It seems the Ubuntu task was created in error.