[reSIProcate] transaction bug in Client Non-INVITE transaction (on retransmission)

[Jason Fischl]

Found an old bug in the TransactionState for Client Non-Invite transactions:

A sends SUBSCRIBE to B
--network latency--
A retransmits SUBSCRIBE to B
B sends 407 to A
B retransmits the 407 to A

The bug is that the stack currently notifies the TU of the 407 that is
retransmitted. It should just eat it since it has already been reported to
the TU once already.