it was recently brought to my attention that the documented method
for using the dbconfig-common hooks in a maintainer's postrm script
was non-compliant wrt policy 7.2. policy stipulates that packages
can not require use of programs from any non-essential packages
in the postrm/purge phase.
unfortunately, the example packages used as guidelines didn't
make any checks to safeguard this, so i suspect most/all of
the packages using dbconfig-common do not either. since these
are rc-bugs, i don't think the lintian route is the correct path and
plan to file the bugs in the next few days.