If six.moves has been imported, finding.find_classes may cause an ImportErrors

[gpshead]

The 'six' library includes a six.moves package that sets up a meta importer import hook to lazily load a bunch of modules only when they are first accessed. The finding.find_classes code when looping over sys.modules (via modules=ALL_IMPORTED_MODULES) is tripped up by this because as soon as it starts trying to introspect the six.moves module, it triggers lazy loading of a bunch of modules which may or may not be present in the systems given Python installation (common examples of modules that'll show up in the resulting ImportError messages: gdbm and Tkinter)

A workaround for this is to filter the list and avoid module names that start with 'six.'. Very hacky, agreed. Possibly worth considering a bug in https://pypi.python.org/pypi/six but given what it is trying to do I think code just needs to learn to play together. (i've encountered one other piece of code with this same problem due to six.moves having been imported)

I'm mailing you a CL internally, I'll let you push it upstream.

[csprabala]

Any idea when this fix will be pushed?