What is happening on buildfarm member dugong?

dugong has been failing contribcheck repeatably for the last day or so,
with a very interesting symptom: CREATE DATABASE is failing with

ERROR: could not fsync segment 0 of relation 1663/40960/41403: No such file or directory
ERROR: checkpoint request failed
HINT: Consult recent messages in the server log for details.

I'd think we broke something in fsync cancellation signalling, except
that AFAICS there were no CVS commits at all between the last working
build at 2007-09-09 23:05:01 UTC and the first failure at 2007-09-10
00:45:27 UTC (and even if I got the timezone conversion wrong, there are
no nearby commits in the backend/storage area). Has this machine had
any system-software updates around then? Can anyone suggest another
theory?

regards, tom lane