Some packages currently refuse to be packaged, often because they
require a special uid or gid.  The postgresql package comes to mind as
a perfect example.  This is annoying for people who have the ids
already and want to compile the stuff on one machine before shipping
the package tarball to another for installation.

Would one solution be to incorporate a mechanism for specifying
uid/gid prerequisites.  For example, if bsd.pkg.mk could make use of
something like

	  REQUIRES_UID=	${POSTGRES_USER}
	  REQUIRES_GID=	${POSTGRES_GROUP}

to determine whether installation/packaging was ok, the problem would
be solved and packages could be made on suitable systems while
maintaining the current behavior if not.

This would probably also entail some directive in PLIST so that
installation of a package could also be dependent on the preexistence
of the right uid/gid pair.

Is this a reasonable thing to implement within the package system?

Cheers,
Brook