Yes, that seems to be it.
Currently the configure hook for core at revision 1689 does this:
# check if we have core support and exit cleanly if not
if ! systemctl --version >/dev/null 2>&1; then
echo "Cannot run systemctl - is core-support available?"
exit 0
fi
This check is insufficient for systems that don’t have apparmor enabled. The later versions of snapd have a fix so regardless if we update core to fix the script (to make the check more generic) or if we update it not to need the check in the first place, the result is the same.
EDIT: For some more context, this is the state of the system when this happens:
qemu:debian-9-64 .../tests/upgrade/basic# snap version
snap 2.24
snapd 2.24
series 16
debian 9
kernel 4.9.0-2-amd64
qemu:debian-9-64 .../tests/upgrade/basic# snap list
Name Version Rev Developer Notes
core 16-2 1689 canonical -
qemu:debian-9-64 .../tests/upgrade/basic# snap changes
ID Status Spawn Ready Summary
1 Doing 2017-05-02T21:11:42Z - Install "test-snapd-tools" snap
2 Done 2017-05-02T21:12:41Z 2017-05-02T21:12:41Z Initialize system state
qemu:debian-9-64 .../tests/upgrade/basic# snap change 1
Status Spawn Ready Summary
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:40Z Download snap "core" (1689) from channel "stable"
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:40Z Fetch and check assertions for snap "core" (1689)
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:41Z Mount snap "core" (1689)
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:41Z Copy snap "core" data
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:41Z Setup snap "core" (1689) security profiles
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:41Z Make snap "core" (1689) available to the system
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:41Z Set automatic aliases for snap "core"
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:42Z Setup snap "core" aliases
Done 2017-05-02T21:11:42Z 2017-05-02T21:12:42Z Start snap "core" (1689) services
Doing 2017-05-02T21:11:42Z - Run configure hook of "core" snap if present
Do 2017-05-02T21:11:42Z - Download snap "test-snapd-tools" (3) from channel "stable"
Do 2017-05-02T21:11:42Z - Fetch and check assertions for snap "test-snapd-tools" (3)
Do 2017-05-02T21:11:42Z - Mount snap "test-snapd-tools" (3)
Do 2017-05-02T21:11:42Z - Copy snap "test-snapd-tools" data
Do 2017-05-02T21:11:42Z - Setup snap "test-snapd-tools" (3) security profiles
Do 2017-05-02T21:11:42Z - Make snap "test-snapd-tools" (3) available to the system
Do 2017-05-02T21:11:42Z - Set automatic aliases for snap "test-snapd-tools"
Do 2017-05-02T21:11:42Z - Setup snap "test-snapd-tools" aliases
Do 2017-05-02T21:11:42Z - Start snap "test-snapd-tools" (3) services
Do 2017-05-02T21:11:42Z - Run configure hook of "test-snapd-tools" snap if present
......................................................................
Setup snap "core" (1689) security profiles
2017-05-02T23:12:41+02:00 INFO snap "core" has bad plugs or slots: core-support-plug (unknown interface)
......................................................................
Make snap "core" (1689) available to the system
2017-05-02T23:12:41+02:00 INFO Requested daemon restart.