PostmasterContext survives into parallel workers!?

I noticed $subject while fooling around with the tqueue.c memory leak
issues. This does not seem like a good idea to me. At the very least,
it's a waste of space that could be used for something else, and at the
worst, it might be a security issue because it leaves security-sensitive
pg_hba and pg_ident information laying about in places where it might be
recoverable (if only through memory-disclosure bugs, which we've had
before and no doubt will have again).

The reason is that the parallel worker launch path contains no equivalent
of PostgresMain's stanza

if (PostmasterContext)
{
MemoryContextDelete(PostmasterContext);
PostmasterContext = NULL;
}

Now, I'm undecided whether to flush that context only in parallel workers,
or to try to make it go away for all bgworkers of any stripe. The latter
seems a little better from a security standpoint, but I wonder if anyone
has a use-case where that'd be a bad idea?

regards, tom lane