Comment 3 for bug 1866597

and it looks not related to the value of 'normal_user'
I copy exist jobs to rewrote a simple job to simulate using pm_test by checkbox remote, and it can reproduce this issue which checkbox remote failed but local run is ok.

job:

plugin: shell
category_id: com.canonical.plainbox::stress
id: stress/reboot_10
requires: executable.name == 'fwts'
 executable.name == 'x-terminal-emulator'
command:
 set -x
 pm_test --checkbox-respawn-cmd $PLAINBOX_SESSION_SHARE/__respawn_checkbox -r 10 --silent --log-level=notset reboot --log-dir=$PLAINBOX_SESSION_SHARE
flags: noreturn
estimated_duration: 900
user: root
environ: PLAINBOX_SESSION_SHARE PM_TEST_DRY_RUN
_description:
 Stress reboot system (10 cycles)

plan:
id: stress-10-reboot-automated
unit: test plan
_name: Power Management reboot and power off stress tests (automated)
_description: Power Management reboot and power off stress tests (automated)
include:
    stress/reboot_10 certification-status=blocker
    stress/reboot_10_log

launcher and config:
https://pastebin.canonical.com/p/8sRyWWsbNt/