grub-install fails if ZFS root pool is in degraded state

[Prakash Surya]

I have a system with a root ZFS pool that's DEGRADED:

    $ zpool status -v
      pool: rpool
     state: DEGRADED
    status: One or more devices has experienced an unrecoverable error. An
            attempt was made to correct the error. Applications are unaffected.
    action: Determine if the device needs to be replaced, and clear the errors
            using 'zpool clear' or replace the device with 'zpool replace'.
       see: https://openzfs.github.io/openzfs-docs/msg/ZFS-8000-9P
    config:

            NAME STATE READ WRITE CKSUM
            rpool DEGRADED 0 0 0
              sda1 DEGRADED 0 0 0 too many errors

    errors: No known data errors

In this state, "grub-install" will fail:

    grub-install: error: failed to get canonical path of `rpool/grub'.

If I apply the following patch, "grub-install" works properly:

    --- a/grub-core/osdep/unix/getroot.c
    +++ b/grub-core/osdep/unix/getroot.c
    @@ -296,7 +296,7 @@ grub_util_find_root_devices_from_poolname (char *poolname)
            && !sscanf (name, "raidz1%u", &dummy)
            && !sscanf (name, "raidz2%u", &dummy)
            && !sscanf (name, "raidz3%u", &dummy)
    - && !strcmp (state, "ONLINE"))
    + && (!strcmp (state, "ONLINE") || !strcmp (state, "DEGRADED")))
              {
            if (ndevices >= devices_allocated)
              {