This post seems to indicate that this was fixed for 8.0, although it may have gotten into one of the later 7.x releases (CB is still running the ancient-by-postgresql-standards 7.4.2 release, just over a year old) as well. Changelogs don't mention it specifically though.
I've rearranged disk usage so this won't happen again, but looking at the list of bugfixes through 7.4.7 I guess I should schedule some downtime to upgrade. Now that 8.0 has its first point release I should probably just bite the bullet and dump/reload to that. Unfortunately, Carnage Blender runs two multi-gig databases now, each with several circular dependencies that make necessary manual fiddling with the dumps before restoring.