Oops, don't add the new unread guess value to the old one but start again with the known messages.
Oops, don't add the new unread guess value to the old one but start again with
the known messages.

svn path=/trunk/kdenetwork/kmail/; revision=130059

lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi