Don't put "Linux" in a root's name if it's already there.
Don't put "Linux" in a root's name if it's already there.

Without this patch, we end up with strings like the following in anaconda's
custom partitioning UI:  "Red Hat Enterprise Linux Server Linux 7.0".
Just in case you didn't know what OS it was.

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