Dozens of 'add security exception' dialogs

Thunderbird greeted me this morning with at least 60 (I stopped counting) "Add Security Exception" dialogs. Each had to be cancelled/closed individually.

To reproduce:
1) Configure an IMAP account that uses SSL. The account should be set up so that Thunderbird regularly checks for mail
2) Configure the SSL cert on the account such that the cert expires at some future date
3) Launch Thunderbird, leave it running. Thunderbird will download mail from the account configured in step 1
4) Wait until the cert expires

Expected results:
Thunderbird presents a dialog, "Add Security Exception", warning about the expired/invalid certificate. It presents this dialog once, leaving it onscreen until the user does something.

Actual results:
Thunderbird presents a dialog, "Add Security Exception", warning about the expired/invalid certificate. The dialog is left onscreen. Thunderbird continues to periodically check for mail. Each time it checks for mail on the account with the expired certificate, it queues up another dialog for display. This can result in dozens or hundreds of dialogs queued up, each of which has to be dismissed individually.

I my case I didn't want to confirm the exception - I wanted to import a new, current certificate for the account in question. There is not an obvious way to do this within the "Add Security Exception" dialog. Therefore I had to cancel each dialog in succession.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: thunderbird 15.0~b1+build1-0ubuntu1
ProcVersionSignature: Ubuntu 3.5.0-8.8-generic 3.5.0
Uname: Linux 3.5.0-8-generic x86_64
AddonCompatCheckDisabled: False
ApportVersion: 2.4-0ubuntu6
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: steve 2162 F.... pulseaudio
BuildID: 20120724152304
Channel: Unavailable
Date: Fri Aug 10 08:43:16 2012
ForcedLayersAccel: False
IfupdownConfig:
 auto lo
 iface lo inet loopback
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Beta amd64 (20100901.1)
IpRoute:
 default via 10.0.1.1 dev wlan0 proto static
 10.0.1.0/24 dev wlan0 proto kernel scope link src 10.0.1.121 metric 9
 169.254.0.0/16 dev wlan0 scope link metric 1000
MostRecentCrashID: bp-06578412-5f07-4f11-a583-3f4332120123
PrefSources: prefs.js
ProcEnviron:
 TERM=xterm
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
Profiles: Profile0 (Default) - LastVersion=15.0/20120724152304 (In use)
RelatedPackageVersions:
 rhythmbox-mozilla 2.97-1ubuntu3
 google-talkplugin 3.2.4.0-1
 totem-mozilla 3.4.3-0ubuntu1
RfKill:
 0: phy0: Wireless LAN
  Soft blocked: no
  Hard blocked: no
RunningIncompatibleAddons: False
SourcePackage: thunderbird
SubmittedCrashIDs: bp-06578412-5f07-4f11-a583-3f4332120123
UpgradeStatus: Upgraded to quantal on 2012-08-07 (2 days ago)
dmi.bios.date: 03/05/08
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP31.88Z.0070.B07.0803051658
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Mac-F4238BC8
dmi.board.vendor: Apple Inc.
dmi.board.version: PVT
dmi.chassis.asset.tag: Asset Tag#
dmi.chassis.type: 2
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-F4238BC8
dmi.modalias: dmi:bvnAppleInc.:bvrMBP31.88Z.0070.B07.0803051658:bd03/05/08:svnAppleInc.:pnMacBookPro3,1:pvr1.0:rvnAppleInc.:rnMac-F4238BC8:rvrPVT:cvnAppleInc.:ct2:cvrMac-F4238BC8:
dmi.product.name: MacBookPro3,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.