Symptom:
SW Version          : 15.0(53496)
Similar Crash Count : 1
Time of First Crash : 2014-Feb-10+20:19:32

Assertion failure at sess/mme/mme-app/app/mme_app_util.c:12231
  Function: mme_app_send_s11_modify_brr_req()
  Expression: sn_status != SN_STATUS_FAILURE
  Proclet: sessmgr (f=87000,i=28)
  Process: card=5 cpu=0 arch=X pid=7223 cpu=~12% argv0=sessmgr
  Crash time: 2014-Feb-10+18:19:32 UTC
  Recent errno: 11 Resource temporarily unavailable
  Stack (80824@0xfffea000):
    [f7e285a1/X] libc.so.6/kill() sp=0xfffeaed8
    [0aa52423/X] sn_assert() sp=0xfffeaf08
    [0776d2ee/X] mme_app_send_s11_modify_brr_req() sp=0xffff6a98
    [077c5f75/X] mme_s1_ho_state_prep_compl_handle_s1_ho_notify() sp=0xffff7568
    [076ff6d9/X] mme_fsm_event_handler() sp=0xffff79c8
    [077c8cba/X] mme_event_handler_s1_ho_procedure() sp=0xffff7a08
    [077008f4/X] mme_procedure_handle_event() sp=0xffff7a48
    [07740d95/X] mme_disp_handle_emm_evt() sp=0xffff7b28
    [07746b4d/X] mme_disp_attached_handle_s1nas_msg() sp=0xffff7bb8
    [076ff6d9/X] mme_fsm_event_handler() sp=0xffff8018
    [076fa693/X] s1_access_recv_msg() sp=0xffff8c28
    [076e8651/X] UzLiSztDatInd() sp=0xffff90d8
    [0c6bfb5f/X] SzUiSztDatInd() sp=0xffff90f8
    [0c6c6776/X] szUiSndDatInd() sp=0xffff9128
    [0c6c0e32/X] szSmRcvEstStMsg() sp=0xffff9198
    [0c6c166a/X] szSmExcMt() sp=0xffff91c8
    [0c6aeed3/X] szLiCOMsgHandler() sp=0xffff9248
    [0c6aea41/X] szLiRcvFromLower() sp=0xffff9438
    [0c6b12d6/X] SzLiSctDatInd() sp=0xffff9598
    [0679f78e/X] sn_ccpu_s1ap_handle_data_ind() sp=0xffff9628
    [0426dfc6/X] sessmgr_mmemgr_data_ind() sp=0xffff9688
    [0426de26/X] sessmgr_handle_mmemgr_req_bulk_data_ind() sp=0xffffaf28
    [0ab041bb/X] sn_msg_arriving_handle() sp=0xffffd5d8
    [0aae1bc5/X] sn_loop_run() sp=0xffffdb68

Conditions:
Collision between an S1 Handover with no SGW relocation waiting for a Create Indirect Data Forwarding Tunnel Response with a Delete Bearer Request to delete one of two attached PDNs.