Odd warning when starting tahoe (nevow/twisted/setuptools noise)

[bewst]

This seems like it could be related to #704, but it's not obvious to me. IIUC twisted isn't part of nevow, nor is nevow part of twisted.

Is this something to worry about?

tahoe-client.tac:4: UserWarning: Module twisted was already imported from /opt/local/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/site-packages/twisted/__init__.pyc, but /opt/local/lib/python2.5/site-packages/Nevow-0.9.32-py2.5.egg is being added to sys.path
  import pkg_resources
STARTING /Users/dave/.tahoe
client node probably started

[warner]

Nope, it's nothing to worry about. It's some sort of setuptools-triggered noise. Nevow can optionally use Twisted, and includes a file that makes it look like it's related to twisted (a plugin of some sort, I think), and I think this confuses setuptools.

We have a test that looks for noise like this (RunNode.test_client_no_noise in source:src/allmydata/test/test_runner.py​), which is marked "TODO", which basically means it will nag us about it forever until we find some way to fix it (possibly by dumping nevow altogether, or dumping setuptools altogether, or by spending a lot of time fixing one or both).

[zooko]

This particular bit of noise is best blamed on nevow, and we submitted a patch to nevow to fix it: ​http://divmod.org/trac/ticket/2830 . It appears that acceptance of that patch is blocked on someone patching nevow's buildbot tests to test the noisiness of nevow when it is installed in that way.