The reason why the completion tests didn't pass was because we had it
already disabled in 2acc258dff.
Meanwhile, beetbox/beets@a07cb83 has moved the file from
test/test_completion.sh to test/rsrc/test_completion.sh.
So this has silently re-enabled the completion tests, which we need to
investigate on our side why they failed in the first place.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>