grub-pc 2.02-2ubuntu8.1 fails in setup with ZFS root filesystem

[Tessa]

on trying to upgrade grub-pc today to version 2.02-2ubuntu8.1, I get the following error on my server with ZFS root:

Setting up grub-pc (2.02-2ubuntu8.1) ...
/usr/sbin/grub-probe: error: failed to get canonical path of `rpool/root'.
dpkg: error processing package grub-pc (--configure):
 installed grub-pc package post-installation script subprocess returned error exit status 1
Errors were encountered while processing:
 grub-pc
E: Sub-process /usr/bin/dpkg returned an error code (1)

ZFS root worked fine with grub-pc prior to this package release, so this feels like a package regression.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: grub-pc 2.02-2ubuntu8.1
ProcVersionSignature: Ubuntu 4.15.0-24.26-generic 4.15.18
Uname: Linux 4.15.0-24-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
Date: Fri Jul 13 10:31:56 2018
InstallationDate: Installed on 2014-11-09 (1341 days ago)
InstallationMedia: Ubuntu-Server 14.10 "Utopic Unicorn" - Release amd64 (20141022.2)
ProcEnviron:
 LANGUAGE=en_CA:en
 TERM=xterm-256color
 PATH=(custom, no user)
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: grub2
UpgradeStatus: Upgraded to bionic on 2018-05-20 (53 days ago)

[Tessa (unit3)]

note: this problem still appears to be present with grub-pc-2.02-2ubuntu8.2.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.