Comment 1 for bug 656149

Rather than depending on watershed, it would be better to detect when we're invoked by cryptdisks_start and not require watershed at all. Watershed is really only required when there's the possibility of two processes trying to decrypt the same disk at the same time; while this might happen with cryptdisks_start, that would be user error rather than an init system bug, and it's probably simpler to not guard against this case.