Use the new syntax for raise statements
Reported by Elessar:
The file nbxmpp/xmpp_stringprep.py uses an old syntax for several raise statements: raise Exception, "text". This syntax is apparently incompatible with Python 3.4.
You should use the new syntax instead: raise Exception("text"). This syntax is compatible with all current versions of Python 2 and 3.
Here is a patch that fixes this issue.