words: Unbound variable nickname in IRCUser for invalid user name

[j2a]

If user send NICK command with non-utf8 non-ascii symbols, IRCUser raises UnboundLocalError:

exceptions.UnboundLocalError: local variable 'nickname' referenced before assignment

patch and test is attached.

[j2a]

Fix for UnboundLocalError and test for it

[exarkun]

Pretty sure j2a meant to do this...

[exarkun]

Thanks.

1. The docstrings for test_utf8Messages and test_wrongUtf8Nick do half of a good job. They should explain the desired behavior as well as explaining the case they are exercising, though.
2. Please separate methods from each other by two blank lines and wrap lines at less than 80 columns.
3. nickname = params[0] isn't likely to raise a UnicodeDecodeError, right? So the line being added inside the try/except could probably go before the try statement begins. It's nice to minimize the amount of code inside try blocks.

Thanks again! It's really great to see you working on this area of Twisted.

[stephsolis]

Addressed review suggestions