Imap4 - issuing a typo causes unhandled exception

New submission from Magneto <None>:

Problem lies in this code (line 5131)
        state = self.state.pop()

If you issue this command for e.g "fetch 1 fulll" (note the 3rd l) 
You will get :
       exceptions.IndexError: pop from empty list
And the client telnet screen gets a :
       3 BAD Server error: pop from empty list

This is because the "l" is treated as a command but the "self.state" is already empty.

Suggested fix : 
                if not self.state :
                    self.remaining = ""
                    break
                




----------
Type     : defect
Component: mail
Keywords : 
Priority : normal
Nosy     : 
----------
http://twistedmatrix.com/trac/ticket/4000