mod_wsgi: import python modules with the same name

This is a follow-up question to import python modules with the same name, but as the two are somewhat unrelated, it's probably better to ask a new question:

I have several python projects and they all have a conf package:

/some_folder/project_1/
  conf/
    __init__.py
    some_source_file.py

/another_folder/project_2/
  conf/
    __init__.py
    another_source_file.py

For each project, I have created a .pth file in the site-packages folder with this contents:

.../site-packages/project_1.pth:
import sys; sys.path.append('/some_folder/project_1/')

.../site-packages/project_2.pth:
import sys; sys.path.append('/another_folder/project_2/')

Now, accessing the conf module works for /some_folder/project_1/:

import conf.some_source_file

but not for /another_folder/project_2/:

import conf.another_source_file
AttributeError: 'module' object has no attribute 'another_source_file'

which is probably due to python only searching the first conf path underneath any folders in sys.path.

I have therefore turned project_1 and project_2 into python packages and added a symlink in either, so I can access both conf packages in a fully qualified fashion:

/some_folder/project_1/
  __init__.py
  project_1 <-- symlink to .
  conf/
    __init__.py
    some_source_file.py

/another_folder/project_2/
  __init__.py
  project_2 <-- symlink to .
  conf/
    __init__.py
    another_source_file.py

In an ordinary python script, I can now import modules from both conf packages:

import project_1.conf.some_source_file
import project_2.conf.another_source_file

However, when I try to do the same within an WSGI application using the mod_wsgi Apache module, the import fails for the second project. Specifically, the wsgi 'start file' (i.e. the one with a wsgi suffix referenced in the WSGIScriptAlias statement in the Apache config file for my virtual server) successfully imports a module in /another_folder/project_2/ which in turn imports project_2/conf/another_source_file.py.

The second import fails, despite the fact that /another_folder/project_2/ is in sys.path. The WSGI application is running in daemon mode.

How can I get this sorted ?

FWIW, this was dealt with on mod_wsgi mailing list and from memory turned out to be caused by presence of both a module and package with same name and was picking up wrong one.