resolved: make sure we initialize t->answer_errno before completing the transaction

We must have the error number around when completing the transaction.
Let's hence make sure we always initialize it *first* (we accidentally
did it once after).

Fixes: #11626
(cherry picked from commit fd8a3017)
(cherry picked from commit 38ae73fa)
(cherry picked from commit 54948d49)
(cherry picked from commit 156570cc)