i wonder all of this, and i tried to reply to myself.
Please correct me if wrong.
Inside debian/ directory, without upstream source ?
no if optional command is not run, yes if it is
Inside debian/ directory, with upstream source ?
no, that would be crazy
Is the optional command in debian/watch line run by the PTS tracker ?
no, too dangerous security-wise, but i had to ask
Jérémy.