CBD-485 fix descriptors leak in jump_to_another_version

Change-Id: Idef3c2d31cc12483b27015e0ea7bb6848d39f512
Reviewed-on: http://review.couchbase.org/31123
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>