Automake's 'make distcheck' gives a failure if the 'make distcheck'
crosses midnight (i.e. it begins on day X, and ends at day X+1),
since it thinks distclean failed:

make[2]: Leaving directory `/var/lib/buildbot/clambb/slave1/distcheck/build/clamav-devel-20100328/_build'
rm -f config.status config.cache config.log configure.lineno config.status.lineno
rm -f Makefile
ERROR: files left in build directory after distclean:
./clamav-devel-20100329.tar.gz
./clamav-devel-20100329.tar.bz2
make[1]: *** [distcleancheck] Error 1

The build started on 2010-03-28 at 23:59:54, and ended at 2010-03-29 at
00:04:02.
Now distcheck expects to find a clamav-devel-20100328.tar.gz file after 'make
distcheck' but it finds a clamav-devel-20100329.tar.gz and fails.

This is a rare condition (build crossing midnight), but it causes a buildbot
to consider a build failed when it shouldn't.