Unreliable retrieve of hardware addresses for v4 MySQL lease backend.
In mysql_lease_mgr.cc getLeaseData() uses the hwaddr_null_ flag to set the hwaddr_ field of v4 leases but this variable is not passed to MySQL as search for it in the v4 code shows (MySqlLease4Exchange ctor and definition, twice in createBindForSend, getLeaseData, but not in createBindForReceive as expected). The fix is simple because the v6 code is correct so just do the same.
Attaching a diff file from my #2870 (closed) debug