Add all /gnu/store/ prefixes found in PYTHONPATH to the prefixes where
site-packages (and .pth files) are searched.

*** Python-2.7.11/Lib/site.py.orig	2016-10-17 23:27:23.746149690 +0200
--- Python-2.7.11/Lib/site.py	2016-10-17 23:44:51.930871644 +0200
***************
*** 65,70 ****
--- 65,82 ----
  
  # Prefixes for site-packages; add additional prefixes like /usr/local here
  PREFIXES = [sys.prefix, sys.exec_prefix]
+ # Guix: Add all /gnu/store-paths in PYTHONPATH--these are all
+ # "prefixes".  This is required to search .pth files in all python
+ # packages contained in /gnu/store which is required to make
+ # .pth-defined namespace packages work.
+ # This is necessary if the packages are not merged into a single
+ # `site-packages` directory (like when using `guix environment`) but
+ # listed in PYTHONPATH (like when running `guix build`).
+ for p in sys.path:
+     if p.startswith('/gnu/store/'):
+         PREFIXES.append(p[:p.find('/', 44)]) # find first pathsep after hash
+ del p
+ 
  # Enable per user site-packages directory
  # set it to False to disable the feature or True to force the feature
  ENABLE_USER_SITE = None
82539c3152a9e2'>refs</a><a class='active' href='/guix/log/gnu/packages/aux-files/guix.vim'>log</a><a href='/guix/tree/gnu/packages/aux-files/guix.vim?id=a8c1d812a030f07dbc22afa12f82539c3152a9e2'>tree</a><a href='/guix/commit/gnu/packages/aux-files/guix.vim?id=a8c1d812a030f07dbc22afa12f82539c3152a9e2'>commit</a><a href='/guix/diff/gnu/packages/aux-files/guix.vim?id=a8c1d812a030f07dbc22afa12f82539c3152a9e2'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/aux-files/guix.vim'>
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<tr><td><span title='2023-11-08 10:28:55 +0200'>2023-11-08</span></td><td><a href='/guix/commit/gnu/packages/aux-files/guix.vim?id=b17567d45c03b7125bfe0255f4ac45d5db81a268'>gnu: vim: Add vim packages to 'package-path' instead of 'runtime-path'.</a><span class='msg-avail'>...<span class='msg-tooltip'>    This is neccesary because vim's built-in plugin manager looks for directories
    under 'package-path' instead of 'runtime-path.' Once we have told vim the
    package-path, it adds all the packages to the runtime-path automatically for us.

* gnu/packages/aux-files/guix.vim: Add paths to packagepath instead of
runtimepath.  Remove code to adjust runtimepath after adding paths.

Signed-off-by: Efraim Flashner &lt;efraim@flashner.co.il&gt;
</span></span></td><td>Jonathan Scoresby</td></tr>