Upgrade test: fail when nothing was upgraded, and retry a lost push

A channel that holds the version the machine already has upgrades
nothing, and every other check passes on a machine that was only
rebooted: rc is in that state today. A twelfth check requires the
Omarchy package to have changed.

Two runs on different branches both push pictures to one branch. The
second to push was refused and its comment never written. The push is
now tried again on top of whatever got there first; each run's folder is
its own, so there is nothing to merge.

test/upgrade-test

@@ -192,6 +192,9 @@ check "No migration was skipped ($(a migrations_skipped) skipped)" test "$(a mig
 check "The system came back from the reboot by itself (came back: $rebooted)" test "$rebooted" = yes
 check "It is a new boot (boot ID $(b boot_id) → $(a boot_id))" test -n "$(a boot_id)" -a "$(a boot_id)" != "$(b boot_id)"
 check "It is on the $channel channel (got: $(a channel))" test "$(a channel)" = "$channel"
+# A channel that holds what the machine already had upgrades nothing, and
+# every other check would pass on a machine that was only rebooted.
+check "Omarchy itself changed ($(b omarchy) → $(a omarchy))" test -n "$(a omarchy)" -a "$(a omarchy)" != "$(b omarchy)"
 check "The running kernel is an installed one ($(a kernel))" test "$(a kernel_is_installed)" = yes
 check "systemd reports the system running (got: $(a system_state))" test "$(a system_state)" = running
 failed="$(a failed_units) $(a failed_user_units)"