[imp] weird name completion behavior

[Liam Hoekenga]

We've noticed a weird behavior when composing messages in 4.2.

If you start typing something on a recipient line (to, cc, bcc), IMP  
will try to expand it using one of your address books.  If you let it  
make a suggestion, and then type in a different domain name, you end  
up with something like this..

     Joe User <juser at umich.edu>@gmail.com

It looks like it's forcibly using it's suggestion, which could be  
counter to user expectations.

Liam