It is customary in the IPA protocol that a a server side
responds with an ID_ACK if the client sends an ID_ACK. Due
to the lack of any protocol specification, it's unclear why
exactly, but we know it does happen.
osmo-remsim-bankd so far failed to implement this, which is
not directly a problem as the only user (osmo-remsim-client)
didn't care. However, when executing TTCN3 test cases,
the IPA_Emulation expects that ID_ACK and related test fail.
Change-Id: Ie55c9d5c435df786e97ec3900837bb21ab80140a
Harald Welte
667d694a38