Comment # 2 on bug 1229997 from Neil Brown

I think the problem is that your 
   /etc/sysconfig/mdadm
has both "MDADM_RAIDDEVICES" set and also "MDADM_SCAN=yes".

I don't think those two make sense together.
This used to work prior to mdadm-4.3 but when we updated past that version the
inconsistent setting are now reported as an error.

We should probably improve the documentation in /etc/sysconfig/mdadm or maybe
automatically resolve the inconsistency in  /usr/libexec/mdadm/mdadm_env.sh