bsc: handover: actually send Handover Detect

Until now, the test went from RR Handover Command directly to RR Handover
Complete, and osmo-bsc didn't mind it. However, the normal handover procedure
requires an RSL Handover Detect to be sent in-between those. Send that.

Change-Id: I6e54edcc3a99e116d852eca8e48c7a5bc685e832
diff --git a/bsc/MSC_ConnectionHandler.ttcn b/bsc/MSC_ConnectionHandler.ttcn
index 0846762..2042979 100644
--- a/bsc/MSC_ConnectionHandler.ttcn
+++ b/bsc/MSC_ConnectionHandler.ttcn
@@ -877,6 +877,10 @@
 			 * before performing a hand-over */
 			f_rslem_resume(RSL1_PROC);
 
+			/* send handover detect */
+			RSL1.send(ts_RSL_HANDO_DET(new_chan_nr));
+			f_sleep(0.3);
+
 			/* send handover complete over the new channel */
 			var PDU_ML3_MS_NW l3_tx := valueof(ts_RRM_HandoverComplete('00'O));
 			RSL1.send(ts_RSL_DATA_IND(new_chan_nr, valueof(ts_RslLinkID_DCCH(0)),