Fix incorrect content handling for truncated archives.
Fix incorrect content handling for truncated archives.

By choping the tarsnap err messages from the content listing and, additionally, forwarding to the user via the detail status message text.

Tarsnap/tarsnap-gui,Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui,shinnok/tarsnap-gui,Tarsnap/tarsnap-gui