Fixed checking status of MD RAID which was just deleted.
Fixed checking status of MD RAID which was just deleted.

The state_file still exists, but returns 'Device or resource busy' upon
reading.

Resolves: rhbz#923788

rhinstaller/blivet,jkonecny12/blivet,rhinstaller/blivet,vojtechtrefny/blivet,rvykydal/blivet,vpodzime/blivet,AdamWill/blivet,vojtechtrefny/blivet,dwlehman/blivet,rvykydal/blivet,AdamWill/blivet,jkonecny12/blivet,dwlehman/blivet,vpodzime/blivet