Ignore errors prefetching database_grant

If database_grant couldn't be prefetched because there was no /root/.my.cnf
this error can be ignored becuase it is tried again when its needed. So packstack
can ignore this error from the puppet apply
https://bugzilla.redhat.com/show_bug.cgi?id=904671

Change-Id: Id255621b1c65e854d2d3f85880d67f98f48a005b
Merge "Ignore errors prefetching database_grant"