02r1_Manage_add: it covers testing 2 scenarios against manage_add.
1. 2 active disks in md array, set 1 disk 'fail' and 'remove' it
from array, then add 1 pure disk into array.
2. 2 active disks in array, add 1 new disk into array directly, now
the 'add' in equal to 'add-spare'.
Signed-off-by: Zhilong Liu <zlliu@suse.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>
Zhilong Liu