plymouth-stop: race condition between rc RUNLEVEL=2 and display manager

while debugging a different bug in lightdm, I noticed that the plymouth-stop job has a race condition. If rc RUNLEVEL=2 is emitted at boot before 'starting lightdm' (etc), a subsequent 'starting lightdm' will not block on the plymouth-stop job to complete, possibly causing the DM to start up before plymouth has been stopped. For a DM that doesn't properly integrate with plymouth, this could cause problems with VTs.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: plymouth 0.8.2-2ubuntu23
ProcVersionSignature: Ubuntu 3.0-1.2-generic 3.0.0-rc3
Uname: Linux 3.0-1-generic x86_64
Architecture: amd64
Date: Thu Jun 30 16:05:18 2011
DefaultPlymouth: /lib/plymouth/themes/ubuntu-logo/ubuntu-logo.plymouth
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
Lsusb:
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
 Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
MachineType: LENOVO 3249CTO
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.0-1-generic root=/dev/mapper/hostname-root ro quiet splash vt.handoff=7
SourcePackage: plymouth
TextPlymouth: /lib/plymouth/themes/ubuntu-text/ubuntu-text.plymouth
UpgradeStatus: Upgraded to oneiric on 2011-06-27 (3 days ago)
dmi.bios.date: 08/23/2010
dmi.bios.vendor: LENOVO
dmi.bios.version: 6QET52WW (1.22 )
dmi.board.name: 3249CTO
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6QET52WW(1.22):bd08/23/2010:svnLENOVO:pn3249CTO:pvrThinkPadX201:rvnLENOVO:rn3249CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 3249CTO
dmi.product.version: ThinkPad X201
dmi.sys.vendor: LENOVO