don't display stage2 missing error as well if the real problem is stage1
don't display stage2 missing error as well if the real problem is stage1

As things stand, if you fail the stage1 check for any reason, I think you will
always also see the "missing stage2" error message - "You have not created a
bootable partition." - even though the problem is really the missing stage1.
This should only display the missing stage2 error if stage1 is OK.

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