mdadm --remove does not remove failed component

[Andrei Caraman]

mdadm 4.2-0ubuntu2 on jammy:

mdadm doesn't remove failed components from raid1 device and returns a 0 exit code. Using the actual device name instead of "failed" or "detached" doesn't make a difference.

root@server:~# cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 sdc2[2] sda2[3] sdb2[4](F)
      975581912 blocks super 1.2 [2/2] [UU]
      bitmap: 1/2 pages [4KB], 262144KB chunk

md9 : active raid1 sdc1[2] sda1[0] sdb1[1](F)
      1046528 blocks super 1.2 [2/2] [UU]

unused devices: <none>
root@server:~# mdadm /dev/md9 -r detached
root@server:~# mdadm /dev/md1 -r detached
root@server:~# mdadm /dev/md9 -r failed
root@server:~# mdadm /dev/md1 -r failed
root@server:~# $?
0: command not found
root@server:~# cat /proc/mdstat
Personalities : [raid1] [linear] [multipath] [raid0] [raid6] [raid5] [raid4] [raid10]
md1 : active raid1 sdc2[2] sda2[3] sdb2[4](F)
      975581912 blocks super 1.2 [2/2] [UU]
      bitmap: 1/2 pages [4KB], 262144KB chunk

md9 : active raid1 sdc1[2] sda1[0] sdb1[1](F)
      1046528 blocks super 1.2 [2/2] [UU]

unused devices: <none>
root@server:~#