Don't show occasionally broken attachment icons.
Don't show occasionally broken attachment icons.

svn path=/trunk/kdenetwork/kmail/; revision=169613

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