[MERGE] Fix Ftp+GSSAPI with newer version of Python-Kerberos

[Aaron Bentley]

Aaron Bentley has voted approve.
Status is now: Approved
Comment:
I found the surrounding code very confusing (what is self.vc?)  But it 
looks like we were explicitly specifying the default, so removing the 
explicitness is fine.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C20081003002157.GA7725%40charis.vernstok.nl%3E
Project: Bazaar