I'm sorting through changes made in our work tree, and came across this commit
that seems just to be an oversight. Shouldn't M_FLOWID be included in M_COPYFLAGS
so that places like m_{move,dup}_pkthdr() carry over the flag in situations like
when we have to prepend a new mbuf pkthdr? The actual flowid value gets copied
over as a part of copying the pkthdr, but the corresponding flag is not set.
Or does somebody have some historical context why M_FLOWID was omitted?