Work around trytond.module not being a real namespace module.

Solution is to add all trytond module's locations to
trytond.modules._path__. This will make trytond.module behave much
like a namespace module.
Adding to __path__ is done in update_egg_modules() to ensure __path__
is updated whenever the list of egg modules is updated.

*** a/trytond/modules/__init__.py	1970-01-01 01:00:01.000000000 +0100
--- b/trytond/modules/__init__.py	2021-12-02 18:12:15.385101986 +0100
***************
*** 38,43 ****
--- 38,46 ----
          import pkg_resources
          for ep in pkg_resources.iter_entry_points('trytond.modules'):
              EGG_MODULES[ep.name] = ep
+             path = os.path.join(ep.dist.location, 'trytond', 'modules')
+             if not path in __path__ and os.path.isdir(path):
+                 __path__.append(path)
      except ImportError:
          pass
  
s='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
<table class='tabs'><tr><td>
<a href='/guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=1345eeb03a25b08d07d9a613531033afd428a8be'>refs</a><a class='active' href='/guix/log/tests/sets.scm'>log</a><a href='/guix/tree/tests/sets.scm?id=1345eeb03a25b08d07d9a613531033afd428a8be'>tree</a><a href='/guix/commit/tests/sets.scm?id=1345eeb03a25b08d07d9a613531033afd428a8be'>commit</a><a href='/guix/diff/tests/sets.scm?id=1345eeb03a25b08d07d9a613531033afd428a8be'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/sets.scm'>
<input type='hidden' name='id' value='1345eeb03a25b08d07d9a613531033afd428a8be'/><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=1345eeb03a25b08d07d9a613531033afd428a8be'>root</a>/<a href='/guix/log/tests?id=1345eeb03a25b08d07d9a613531033afd428a8be'>tests</a>/<a href='/guix/log/tests/sets.scm?id=1345eeb03a25b08d07d9a613531033afd428a8be'>sets.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/tests/sets.scm?id=1345eeb03a25b08d07d9a613531033afd428a8be&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2016-04-03 14:19:09 +0200'>2016-04-03</span></td><td><a href='/guix/commit/tests/sets.scm?id=a9edb211e733b8b34e67ec3b4450567e9376986f'>build: Add a Guile custom test driver using SRFI-64.</a><span class='msg-avail'>...<span class='msg-tooltip'>Before that '.log' files for scheme tests were fragmented and not
included in test-suite.log.  This unifies the semantics of SRFI-64 API
with Automake test suite.

* build-aux/test-driver.scm: New file.
* Makefile.am (SCM_LOG_DRIVER, AM_SCM_LOG_DRIVER_FLAGS): New variables.
(SCM_LOG_COMPILER, AM_SCM_LOG_FLAGS): Delete variables.
(AM_TESTS_ENVIRONMENT): Set GUILE_AUTO_COMPILE to 0.
* test-env.in: Silence guix-daemon.
* doc/guix.texi (Running the Test Suite): Describe how to display the
detailed results.  Bug reports require only 'test-suite.log' file.
* tests/base32.scm, tests/build-utils.scm, tests/builders.scm,
tests/challenge.scm, tests/cpan.scm, tests/cpio.scm, tests/cran.scm,
tests/cve.scm, tests/derivations.scm, tests/elpa.scm,
tests/file-systems.scm, tests/gem.scm, tests/gexp.scm,
tests/gnu-maintenance.scm, tests/grafts.scm, tests/graph.scm,
tests/gremlin.scm, tests/hackage.scm, tests/hash.scm,
tests/import-utils.scm, tests/lint.scm, tests/monads.scm, tests/nar.scm,
tests/packages.scm, tests/pk-crypto.scm, tests/pki.scm,
tests/profiles.scm, tests/publish.scm, tests/pypi.scm,
tests/records.scm, tests/scripts-build.scm, tests/scripts.scm,
tests/services.scm, tests/sets.scm, tests/size.scm, tests/snix.scm,
tests/store.scm, tests/substitute.scm, tests/syscalls.scm,
tests/system.scm, tests/ui.scm, tests/union.scm, tests/upstream.scm,
tests/utils.scm: Don't exit at the end of test groups.
* tests/containers.scm: Likewise.  Use 'test-skip' instead of exiting
with error code 77.
</span></span></td><td>Mathieu Lirzin</td></tr>
<tr><td><span title='2015-01-11 23:50:01 +0100'>2015-01-11</span></td><td><a href='/guix/commit/tests/sets.scm?id=d326767e6417cbaad2856e6641e98dd80311b8c3'>Add (guix sets).</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/sets.scm, tests/sets.scm: New files.sets
* Makefile.am (MODULES, SCM_TESTS): Add them.
</span></span></td><td>Ludovic Courtès</td></tr>