convert mount service to trigger

Good: this means it's not hanging holding the s6 dataase lock.

Bad: it's the ugliest implementation and doesn't deserve to be preserved

(tbf the ugliness is not new)

tests/inout/script.expect

@@ -0,0 +1,47 @@
+set timeout 10
+
+proc chat {instr outstr} {
+    expect {
+        $instr  { send $outstr }
+        timeout { exit 1 }
+    }
+}
+spawn socat -,echo=0,icanon=1 unix-connect:vm/monitor
+set monitor_id $spawn_id
+
+# expect "(qemu)"
+# send "set_link virtio-net-pci.1 off\n"
+# expect "(qemu)"
+# send "set_link virtio-net-pci.0 off\n"
+# expect "(qemu)"
+# send "c\r\n"
+
+spawn socat unix-connect:vm/console -
+set console_id $spawn_id
+
+expect "BusyBox"
+chat "#" "PS1=RE\\ADY_\\ ; stty -echo \r"
+chat "READY_"  "s6-rc -b  -a list\r"
+
+chat "watch-mount" "\r"
+
+set spawn_id $monitor_id
+chat "QEMU" "device_add usb-storage,bus=xhci.0,drive=usbstick\n"
+chat "(qemu)" "version\r"
+
+set spawn_id $console_id
+
+expect {
+  "mounted filesystem" { }
+  timeout { exit 1 }
+}
+
+
+send "\r"
+chat "READY_" "s6-rc -b -a list\r"
+chat "READY_" "cat /proc/mounts\r"
+
+expect {
+  "/srv" { }
+  timeout { exit 1 }
+}