When executing a script from a UNC path, e.g. //myhost/exports/a.py, 
r"\\myhost\exports" gets prepended to sys.path.  But it doesn't work.  
This means that in a.py, "import b" will fail even though b.py is 
present in the same directory.

The workaround is to manually prepend a backslass to the UNC path in 
sys.path.

Note the related defect: http://bugs.python.org/issue954115
This intdoruces two functions for testing UNC paths, but it appears 
that these functions are nowhere used!