fix MSC.TC_lu_clear_request: allow LU Reject, forbid 2nd Clear Cmd

When the MS sends a Clear Request in the middle of a Location Updating, it
should be permitted for the MSC to send a Location Updating Reject back. Extend
with an alt that also allows a LU reject before the Clear Command.

The test explicitly hints at https://osmocom.org/issues/2862 which rightfully
forbids the MSC to send a second Clear Command after the first is completed.
However, this test so far explicitly permits a second Clear Command, so it was
probably passing in error all the time. Set verdict to failure if a second
Clear Command is received before the DISC_IND.

This changes the test verdict to failure with current osmo-msc master,
rightfully so; the failure will be fixed by the upcoming MSC subscr conn FSM
refactoring.

Change-Id: I7bc5555b829d61b0a2529107bc9b58446865545d
diff --git a/msc/expected-results.log b/msc/expected-results.log
index 3945a5f..92c38a0 100644
--- a/msc/expected-results.log
+++ b/msc/expected-results.log
@@ -20,7 +20,12 @@
   <testcase classname='MSC_Tests' name='TC_lu_and_mo_call' time='4.291881'/>
   <testcase classname='MSC_Tests' name='TC_lu_auth_sai_timeout' time='6.032964'/>
   <testcase classname='MSC_Tests' name='TC_lu_auth_sai_err' time='1.028503'/>
-  <testcase classname='MSC_Tests' name='TC_lu_clear_request' time='2.029726'/>
+  <testcase classname='MSC_Tests' name='TC_lu_clear_request' time='2.067166'>
+    <failure type='fail-verdict'>Got a second Clear Command, only one expected
+      MSC_Tests.ttcn:1832 MSC_Tests control part
+      MSC_Tests.ttcn:704 TC_lu_clear_request testcase
+    </failure>
+  </testcase>
   <testcase classname='MSC_Tests' name='TC_lu_disconnect' time='2.028908'/>
   <testcase classname='MSC_Tests' name='TC_lu_by_imei' time='6.030599'/>
   <testcase classname='MSC_Tests' name='TC_lu_by_tmsi_noauth_unknown' time='1.246818'/>