sgsn: Introduce test TC_attach_req_id_req_ra_update

The scenario in this test triggers a crash in osmo-sgsn fixed by
osmo-sgsn.git I64fa5cf1b427d3abb99e553e584897261a827ce6.

With that osmo-sgsn patch applied, the process doesn't crash anymore but
the test still fails due to an XID message being sent with a new
yet-not-seen-by-ttcn3 TLLI and as a result TTCN3 BSSGP_Emulation fails:
BSSGP_Emulation.ttcn:390 setverdict(fail): none -> fail reason: "Couldn't find Component for TLLI 'FE791757'O", new component reason: "Couldn't find Component for TLLI 'FE791757'O"

Other than that, the test runs fine. It still needs to be clarified
whether the new TLLI sent by osmo-sgsn is expected and test needs to be
fixed, or whether it's an sgsn bug.

Related: OS#3957, OS#4245
Change-Id: Id5554a91a8bda712e282c5a3e9e30fb0ca1ec0e8
2 files changed