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
='/guix/refs/?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8'>refs</a><a class='active' href='/guix/log/gnu/packages/mercury.scm?showmsg=1'>log</a><a href='/guix/tree/gnu/packages/mercury.scm?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8'>tree</a><a href='/guix/commit/gnu/packages/mercury.scm?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8'>commit</a><a href='/guix/diff/gnu/packages/mercury.scm?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/packages/mercury.scm'>
<input type='hidden' name='id' value='fff4daa5c2bfbf42c7ad2519f500bd254ce880a8'/><input type='hidden' name='showmsg' value='1'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8&amp;showmsg=1'>root</a>/<a href='/guix/log/gnu?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8&amp;showmsg=1'>gnu</a>/<a href='/guix/log/gnu/packages?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8&amp;showmsg=1'>packages</a>/<a href='/guix/log/gnu/packages/mercury.scm?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8&amp;showmsg=1'>mercury.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/mercury.scm?id=fff4daa5c2bfbf42c7ad2519f500bd254ce880a8'>Collapse</a>)</th><th class='left'>Author</th></tr>
<tr class='logheader'><td><span title='2021-12-13 17:48:25 +0100'>2021-12-13</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/mercury.scm?id=8394619baceb118df92e355377fd543bb1aa501a'>gnu: Simplify package inputs.</a></td><td>Ludovic Courtès</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
This commit was obtained by running:

  ./pre-inst-env guix style

without any additional argument.


</td></tr>
<tr class='logheader'><td><span title='2020-11-25 16:40:29 -0600'>2020-11-25</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/mercury.scm?id=8b928a3931cafddb291152bc259b634ab3ab441b'>gnu: mercury: Update to 20.06.1.</a></td><td>Brett Gilio</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/mercury.scm (mercury): Update to 20.06.1.


</td></tr>
<tr class='logheader'><td><span title='2020-11-25 16:40:01 -0600'>2020-11-25</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/mercury.scm?id=4b4fa892cb0fbb98af4606c7a1d55aa09d3eb715'>gnu: mercury-minimal: Update to 20.06.1.</a></td><td>Brett Gilio</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/mercury.scm (mercury-minimal): Update to 20.06.1.


</td></tr>
<tr class='logheader'><td><span title='2020-09-30 09:28:26 +0300'>2020-09-30</span></td><td class='logsubject'><a href='/guix/commit/gnu/packages/mercury.scm?id=1628d57bb5c6ab30a04202c229de642b94faac85'>gnu: Fix package references.</a></td><td>Efraim Flashner</td></tr>
<tr class='nohover-highlight'><td/><td colspan='3' class='logmsg'>
* gnu/packages/algebra.scm (iml)[inputs]: Correctly refer to package
inputs.
* gnu/packages/astronomy.scm (xplanet),
* gnu/packages/audio.scm (redkite, libaudec, lv2lint, lv2toweb),
* gnu/packages/bioconductor.scm (r-cummerbund),
* gnu/packages/chicken.scm (chicken),
* gnu/packages/conky.scm (conky),
* gnu/packages/cran.scm (r-latex2exp),
* gnu/packages/crates-io.scm (rust-rgb),
* gnu/packages/databases.scm (mariadb),
* gnu/packages/diffoscope.scm (reprotest),
* gnu/packages/file-systems.scm (glusterfs),
* gnu/packages/finance.scm (electron-cash),
* gnu/packages/games.scm (rinutils, ksudoku, kdiamond, kigo),
* gnu/packages/geo.scm (grass),
* gnu/packages/gnome.scm (libmediaart, gnome-contacts, geoclue),
* gnu/packages/gnucash.scm (aqbanking),
* gnu/packages/image.scm (mtpaint),
* gnu/packages/kde-internet.scm (kopete, ktorrent),
* gnu/packages/kde-utils.scm (kmousetool, kmouth, kronometer),
* gnu/packages/linphone.scm (liblinphone),
* gnu/packages/maths.scm (ppl),
* gnu/packages/mercury.scm (mercury-minimal),
* gnu/packages/music.scm (bjumblr, bschaffl, lsp-plugins,
spectacle-analyzer, helm, tap-lv2, wolf-shaper, shiru-lv2),
* gnu/packages/networking.scm (restinio),
* gnu/packages/prolog.scm (swi-prolog),
* gnu/packages/python-web.scm (gunicorn),
* gnu/packages/python-xyz.scm (python-docusign-esign),
* gnu/packages/ruby.scm (ruby-cucumber, ruby_version, ruby-addressable),
* gnu/packages/sagemath.scm (python-cypari2),
* gnu/packages/skarnet.scm (s6-linux-init),
* gnu/packages/vpn.scm (sshuttle),
* gnu/packages/web.scm (libcyaml),
* gnu/packages/xdisorg.scm (kbdd),
* gnu/packages/xorg.scm (xpra): Same.


</td></tr>