Dear Maintainer,

please see the bug #1069182 in initscripts for the background.

To keep device-mapper controlled drives records from deletion at udev base
cleanup, the udev rules for adding them need to specify "db_persist" option.
This was already done in lvm2 upstream, but the patch is pretty trivial, so I
don't think it needs waiting for the upstream release. I modified the patch so
it applies to the current Debian git version.