logilab-common #122443 Support __path__ in modutils [validation pending]

As per the following docs:

http://docs.python.org/2/tutorial/modules.html#packages-in-multiple-directories

python packages (__init__.py files) can update their __path__ variable to contain a list of different directories. This allows developers to have different parts of their package live in different directories.

The function _module_file() in modutils.py, when handling package files, assumes that the "path = [mp_filename]" (line 636). This could support the __path__ mechanism by loading the module and then setting "path = module.__path__".

The following patch has been tested and works as intended.

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> mod0 = modpath[0]
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< _, mp_filename, mp_desc = find_module(modpath[0], path)
---
> mp_file, mp_filename, mp_desc = find_module(modpath[0], path)
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< path = [mp_filename]
---
> module = load_module(mod0, mp_file, mp_filename, mp_desc)
> path = module.__path__