grub2-install fails to install the boot loader on a newly replaced raid member disk.

Issue

• grub2-install fails to write the boot loader on a newly replaced disk used by mdraid with the error:

  grub2-install: error: unknown filesystem.
  

• The failure appears randomly, but once it appears, it is persistent until the system is rebooted or caches are dropped (more details in the "Resolution" section)