Make sure a new auth tuple is initialized after
db_get_lastauthtuple_for_subscr() returns an error, i.e. if no tuple is present
for the subscriber yet.
Before this patch, the first key_seq depended on the typically uninitialized
value that was present in auth tuple's key_seq upon calling
auth_get_tuple_for_subscr().
The very first key_seq used for a new subscriber will now always be 0. Before,
it used to be mostly 1 ("(0 + 1) % 7"), but depended on whether the key_seq was
indeed initialized with 0, actually by random.
Neels Hofmeyr
a33fce1cb3