Tolerate devices with no filesystem UUID returned by os-prober

Tolerate devices with no filesystem UUID returned by os-prober

* util/grub.d/30_os-prober.in: Tolerate devices with no filesystem
UUID.  Other parts of grub-mkconfig tolerate these, they were
previously allowed here up to commit
55e706c918922def17f5012c23cfe88c4c645208, and they can arise in
practice when the system has active LVM snapshots.
Fixes Ubuntu bug #1287436.

Origin: upstream, http://git.savannah.gnu.org/gitweb/?p=grub.git;a=commitdiff;h=3a310e842fb7a9818c2e7cf0f4118f13660871d2
Bug-Ubuntu: https://bugs.launchpad.net/bugs/1287436
Forwarded: not-needed
Last-Update: 2014-04-10

Patch-Name: tolerate-lvm-snapshots.patch