Don't waste time looking for devices dependent on leaf devices.
Don't waste time looking for devices dependent on leaf devices.

Also remove hack to include logical partitions as deps of extended
partitions from before they had a proper dependsOn relation.

Related: rhbz#890171

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