Something is rotten in the state of Denmark...

Observe these recent buildfarm failures:

http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mule&dt=2015-03-21%2000%3A30%3A02
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=guaibasaurus&dt=2015-03-23%2004%3A17%3A01
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=mule&dt=2015-03-31%2023%3A30%3A02

Three similar-looking failures, on two different machines, in a regression
test that has existed for less than three weeks.  Something is very wrong.

What's worse, the failure does not look like something that could have
been directly provoked by commit 31eae6028eca4365e7165f5f33fee1ed0486aee0;
I'm afraid it's just falling victim to a bug that may have been there for
awhile.  Given the evidently low probability of triggering the bug, it
may be hard to isolate :-(
        regards, tom lane