Symptom
NCE remains in state STALE after receiving NA with S flag set to 0.
Conditions
1. Send echo request from a host to UUT such that UUT creates NCE for that host IPv6 address and sets its state to INCMP.
2. UUT sends NS to multicast address but host instead of replying with NA that has S flag set to 1, replies with NA with S flag set to 0.
3. UUT should move the state from INCMP to STALE and reply to echo request.
4. UUT should move the state of NCE from STALE to DELAY and wait for DELAY_FIRST_PROBE_TIME before sending NS to unicast address.
