Anyone else noticed: bgfsck doesn't bgfsck non-root 'a' partitions?

fsck has logic to force a full preening fsck of '/', permitting background
file system fsck only for non-root file systems.  For the past few weeks,
I've been wondering why it takes *so* *long* to fsck the root file system
of one of my boxes at work, only to find out that the reason is that it's
running a non-background fsck on /dev/da1s1a, which is an 'a' partition,
but not the root file system (/dev/da0s1a).  It successfully uses bgfsck
on /var and /usr, but not /local0.  So it sounds like the logic in fsck is
simply guessing that any 'a' partition needs a foreground fsck.  This
might be a problem if you wanted to background fsck a multi-terabyte
/bigpartition for exactly the reason bgfsck was introduced. :-)  Has
anyone else run into this, or perhaps want to fix it?

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert_at_fledge.watson.org      Principal Research Scientist, McAfee Research