[Evolution] wind back to older cvs version

[Bill Kenworthy <billk iinet net au>]

I have just built latest cvs (yesterday) on two systems and now cannot
open attachments on either (mail handler crashes when icon clicked). 
How can I wind the downloaded cvs back to a version a week ago which
worked fine so I can fault find this (and read my mail!) as I have been
building a lot of stuff lately and not totally sure the problem is
actually within evo.

BillK