From Jc email - April 2d:

Folks,

Considering that PythonQt exposed the flag PythonQt::IgnoreSiteModule, this one is now used.

See https://github.com/Slicer/Slicer/blob/master/Base/QTCore/qSlicerCorePythonManager.cxx#L40

The associated CTK commit is the following: https://github.com/commontk/CTK/commit/dde2498274b9fc115838fcb5757ec5b1577975ea

Within PythonQt it self, we can also observe that Py_NoSiteFlag code is used: https://github.com/commontk/PythonQt/blob/patched/src/PythonQt.cpp#L164

Using Py_NoSiteFlag is the conventional python way to disable/enable (if not set) the loading of the site module. See http://hg.python.org/cpython/file/d3a82a26c705/Python/pythonrun.c#l79
and more particularly the method initSite: http://hg.python.org/cpython/file/d3a82a26c705/Python/pythonrun.c#l717

I also noticed that there is the python flag: Py_NoUserSiteDirectory, some research will have to be made to find out what the proper use of this flag.

All of that said, adding a try/catch may is probably not the appropriate solution, indeed the module is 'site.py' is by default available on properly installed Slicer python. It's part of the standard list of module. See http://hg.python.org/cpython/file/d3a82a26c705/Lib/site.py

Considering that Dominique already reported on issue associated with python on Debian Testing platform (similar to Ubuntu 12.04), I would suggest to push investigation into that direction. See http://na-mic.org/Bug/view.php?id=1850

The issue probably related to an incorrect python path ... or mis-installed Slicer python or ...

Is this still an issue ? Could you provide more details allowing to reproduce the problem ?

I am not able to reproduce this behaviour anymore. I am closing this issue.