beets: Add patch for fixing bucket tests.

See, that's why I hate the gregorian calendar and new years eve: People
tend to celebrate things that are absolutely irrelevant, like this
comment.

The test however assumed that either beets or its test suite would never
survive 2015, so this test should assure it won't survive in >= 2015 :-)

Anyway, the patch is from upstream master, so we can drop it once 1.3.10
is released.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>