Merge banana-receive-wrong-dialect-7662

Author: wolfgang61, exarkun
Reviewer: exarkun
Fixes: #7662

Check the active Banana dialect before processing dialect-specific features in
the Banana protocol implementation.  Previously features of the PB dialect
could be used even when the None dialect was active.


git-svn-id: svn://svn.twistedmatrix.com/svn/Twisted/trunk@43224 bbbe8e31-12d6-0310-92fd-ac37d47ddeeb