child paused by SIGTSTP fails to cause wait() to report WSTOPPED

A regression was identified by the Upstart testsuite:

Testing job_process_handler()
...with unknown pid
...with running process
...with kill timer
...with restarting process
...with pre-start process
...with failed pre-start process
...with killed pre-start process
...with respawn of running service process
...with respawn of running task process
...with too many respawns of running process
...with normal exit of running respawn process
...with respawn of service process and zero exit code
...with respawn of task process and zero exit code
...with abnormal exit of running process
...with killed running process
...with normal exit of running process
...with normal signal killed running process
...with running task and zero exit
...with post-stop process
...with failed post-stop process
...with stopping task failure after failure
...with post-start process
...with running process in post-start state
...with running process while post-start running
...with running then post-start process
...with failed running then post-start process
...with respawn of running while post-start process
...with pre-stop process
...with running process in pre-stop state
...with running process while pre-stop running
...with respawn of running while pre-stop process
...with running process while stopping
...with stopped non-main process
...with stopped main process outside of spawned
...with stopped main process for non-wait job
...with stopped main process but wrong signal
test_job_process: tests/test_job_process.c:3740: test_handler: Assertion `(waitid (P_PID, pid, &info, 2 | 0x01000000)) == 0' failed.
/bin/bash: line 5: 11151 Aborted (core dumped) ${dir}$tst
FAIL: test_job_process

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.37-10-generic 2.6.37-10.24
Regression: Yes
Reproducible: Yes
ProcVersionSignature: Ubuntu 2.6.37-10.24-generic 2.6.37-rc6
Uname: Linux 2.6.37-10-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
AplayDevices:
 shm_open() failed: Permission denied
 **** List of PLAYBACK Hardware Devices ****
 card 0: Intel [HDA Intel], device 0: ALC268 Analog [ALC268 Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: kees 4631 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xe0420000 irq 43'
   Mixer name : 'Realtek ALC268'
   Components : 'HDA:10ec0268,80860000,00100003'
   Controls : 17
   Simple ctrls : 11
Date: Wed Dec 22 10:35:25 2010
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 LC_MESSAGES=en_US.utf8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-2.6.37-10-generic root=/dev/mapper/systemvg-root2lv ro vt.handoff=7 quiet splash
RelatedPackageVersions: linux-firmware 1.44
RfKill:

SourcePackage: linux
WpaSupplicantLog:

dmi.bios.date: 09/22/2008
dmi.bios.vendor: Intel Corp.
dmi.bios.version: JOQ3510J.86A.0954.2008.0922.2331
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: DQ35JO
dmi.board.vendor: Intel Corporation
dmi.board.version: AAD82085-800
dmi.chassis.type: 3
dmi.modalias: dmi:bvnIntelCorp.:bvrJOQ3510J.86A.0954.2008.0922.2331:bd09/22/2008:svn:pn:pvr:rvnIntelCorporation:rnDQ35JO:rvrAAD82085-800:cvn:ct3:cvr: