Cope with / being on a ZFS root dataset

Cope with / being on a ZFS root dataset

If / is on the root dataset in a ZFS pool, then ${bootfs} will be set to
"/" (whereas if it is on a non-root dataset, there will be no trailing
slash).  Passing "root=ZFS=${rpool}/" will fail to boot, but
"root=ZFS=${rpool}" works fine, so strip the trailing slash.

Fixes: https://savannah.gnu.org/bugs/?52746
Tested-by: Fejes József <jozsef.fejes@gmail.com>
Signed-off-by: Colin Watson <cjwatson@ubuntu.com>
Bug: https://savannah.gnu.org/bugs/?52746
Bug-Debian: https://bugs.debian.org/886178
Last-Update: 2018-10-29

Patch-Name: zfs-root-dataset.patch

Gbp-Pq: Name zfs-root-dataset.patch