PVS-Studio warning V666 for Source SDK

void CMultiplayRules::DeathNotice( .... )
{
  ....
  else if ( strncmp( killer_weapon_name, "NPC_", 8 ) == 0 )
  ....
}

This suspicious code was found in Source SDK project by PVS-Studio static code analyzer.
Warning message is:
V666 Consider inspecting third argument of the function 'strncmp'. It is possible that the value does not correspond with the length of a string which was passed with the second argument. Server (HL2) multiplay_gamerules.cpp 860

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/