I'm having another one of those ill defined probs, but thought I'd mention
it in case anyone else has some clues. Essentially during a make build with
nbuildjobs=6 gets me a:

make: make: don't know how to make ---. Stop

somewhere, eg this morning after --- dependall-usr.sbin ---
but of course I can't be sure which process generated it. My usual is then
to UPDATE=1 NBUILDJOBS=1 to see where the problem happened (only one
process) and all completes successfully => no clue where it's going wrong..

Cheers,

Patrick