Currently if clvmd is running and user issues vgscan,

Currently if clvmd is running and user issues vgscan,
the device cache file is dumped both in vgscan and clvmd process.

Unfortunately, clvmd calls lvmcache_label_scan,
it properly destroys persistent filter, but during
persistent_filter_dump it merges old cache content back!

This causes that change in filters is not properly propagated
into device cache after vgscan on cluster.
(Only new devices are added.)

https://bugzilla.redhat.com/show_bug.cgi?id=591861