Testcase found while fuzzing mozilla-central rev 0d591d3bc997 (built with: --enable-debug --enable-fuzzing).

Testcase can be reproduced using the following commands:

$ pip install fuzzfetch grizzly-framework
$ python -m fuzzfetch --build 0d591d3bc997 --debug --fuzzing -n firefox
$ python -m grizzly.replay ./firefox/firefox testcase.html

Assertion failure: IsAncestor(aOne, aTwo) || IsAncestor(aTwo, aOne), at /builds/worker/workspace/obj-build/dist/include/nsDisplayList.h:193

    ==3720950==ERROR: UndefinedBehaviorSanitizer: SEGV on unknown address 0x000000000000 (pc 0x7f9b77bae613 bp 0x7ffe84df8380 sp 0x7ffe84df8030 T3720950)
    ==3720950==The signal is caused by a WRITE memory access.
    ==3720950==Hint: address points to the zero page.
        #0 0x7f9b77bae613 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp
        #1 0x7f9b7bc2fb10 in CreateWebRenderCommandsNewClipListOption /layout/painting/nsDisplayList.cpp:4655:30
        #2 0x7f9b7bc2fb10 in mozilla::nsDisplayMasksAndClipPaths::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:8207:3
        #3 0x7f9b77baf097 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(mozilla::nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::nsDisplayListBuilder*) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1804:41
        #4 0x7f9b77bad9c0 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp:2067:7
        #5 0x7f9b7bc1f7a6 in CreateWebRenderCommandsNewClipListOption /layout/painting/nsDisplayList.cpp:4655:30
        #6 0x7f9b7bc1f7a6 in CreateWebRenderCommands /layout/painting/nsDisplayList.h:4941:12
        #7 0x7f9b7bc1f7a6 in mozilla::nsDisplayOwnLayer::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:5281:22
        #8 0x7f9b7bc210b7 in mozilla::nsDisplayFixedPosition::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:5487:29
        #9 0x7f9b77baf097 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(mozilla::nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::nsDisplayListBuilder*) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1804:41
        #10 0x7f9b77bad9c0 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp:2067:7
        #11 0x7f9b7bc1e259 in CreateWebRenderCommandsNewClipListOption /layout/painting/nsDisplayList.cpp:4655:30
        #12 0x7f9b7bc1e259 in CreateWebRenderCommands /layout/painting/nsDisplayList.h:4941:12
        #13 0x7f9b7bc1e259 in mozilla::nsDisplayBlendMode::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:5063:29
        #14 0x7f9b77baf097 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(mozilla::nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::nsDisplayListBuilder*) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1804:41
        #15 0x7f9b77bad9c0 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp:2067:7
        #16 0x7f9b7bc1ef12 in CreateWebRenderCommandsNewClipListOption /layout/painting/nsDisplayList.cpp:4655:30
        #17 0x7f9b7bc1ef12 in CreateWebRenderCommands /layout/painting/nsDisplayList.h:4941:12
        #18 0x7f9b7bc1ef12 in mozilla::nsDisplayBlendContainer::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:5175:29
        #19 0x7f9b77baf097 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(mozilla::nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::nsDisplayListBuilder*) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1804:41
        #20 0x7f9b77bad9c0 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp:2067:7
        #21 0x7f9b7bc2fb10 in CreateWebRenderCommandsNewClipListOption /layout/painting/nsDisplayList.cpp:4655:30
        #22 0x7f9b7bc2fb10 in mozilla::nsDisplayMasksAndClipPaths::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:8207:3
        #23 0x7f9b77baf097 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(mozilla::nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::nsDisplayListBuilder*) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1804:41
        #24 0x7f9b77bad9c0 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp:2067:7
        #25 0x7f9b7bc1e259 in CreateWebRenderCommandsNewClipListOption /layout/painting/nsDisplayList.cpp:4655:30
        #26 0x7f9b7bc1e259 in CreateWebRenderCommands /layout/painting/nsDisplayList.h:4941:12
        #27 0x7f9b7bc1e259 in mozilla::nsDisplayBlendMode::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:5063:29
        #28 0x7f9b77baf097 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(mozilla::nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::nsDisplayListBuilder*) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1804:41
        #29 0x7f9b77bad9c0 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp:2067:7
        #30 0x7f9b7bc1ef12 in CreateWebRenderCommandsNewClipListOption /layout/painting/nsDisplayList.cpp:4655:30
        #31 0x7f9b7bc1ef12 in CreateWebRenderCommands /layout/painting/nsDisplayList.h:4941:12
        #32 0x7f9b7bc1ef12 in mozilla::nsDisplayBlendContainer::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:5175:29
        #33 0x7f9b77baf097 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(mozilla::nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::nsDisplayListBuilder*) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1804:41
        #34 0x7f9b77bad9c0 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp:2067:7
        #35 0x7f9b7bc1f7a6 in CreateWebRenderCommandsNewClipListOption /layout/painting/nsDisplayList.cpp:4655:30
        #36 0x7f9b7bc1f7a6 in CreateWebRenderCommands /layout/painting/nsDisplayList.h:4941:12
        #37 0x7f9b7bc1f7a6 in mozilla::nsDisplayOwnLayer::CreateWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::layers::RenderRootStateManager*, mozilla::nsDisplayListBuilder*) /layout/painting/nsDisplayList.cpp:5281:22
        #38 0x7f9b77baf097 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommands(mozilla::nsDisplayItem*, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::layers::StackingContextHelper const&, mozilla::nsDisplayListBuilder*) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1804:41
        #39 0x7f9b77bad9c0 in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool) /gfx/layers/wr/WebRenderCommandBuilder.cpp:2067:7
        #40 0x7f9b77babf27 in mozilla::layers::WebRenderCommandBuilder::BuildWebRenderCommands(mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, mozilla::nsDisplayList*, mozilla::nsDisplayListBuilder*, mozilla::layers::WebRenderScrollData&, WrFiltersHolder&&) /gfx/layers/wr/WebRenderCommandBuilder.cpp:1725:5
        #41 0x7f9b77bc0744 in mozilla::layers::WebRenderLayerManager::EndTransactionWithoutLayer(mozilla::nsDisplayList*, mozilla::nsDisplayListBuilder*, WrFiltersHolder&&, mozilla::layers::WebRenderBackgroundData*, double) /gfx/layers/wr/WebRenderLayerManager.cpp:363:30
        #42 0x7f9b7bc0e360 in mozilla::nsDisplayList::PaintRoot(mozilla::nsDisplayListBuilder*, gfxContext*, unsigned int, mozilla::Maybe<double>) /layout/painting/nsDisplayList.cpp:2292:18
        #43 0x7f9b7b8758ce in nsLayoutUtils::PaintFrame(gfxContext*, nsIFrame*, nsRegion const&, unsigned int, mozilla::nsDisplayListBuilderMode, nsLayoutUtils::PaintFrameFlags) /layout/base/nsLayoutUtils.cpp:3446:9
        #44 0x7f9b7b7e79e7 in mozilla::PresShell::PaintInternal(nsView*, mozilla::PaintInternalFlags) /layout/base/PresShell.cpp:6414:5
        #45 0x7f9b7b43598b in nsViewManager::ProcessPendingUpdatesPaint(nsIWidget*) /view/nsViewManager.cpp:440:18
        #46 0x7f9b7b4354ab in nsViewManager::ProcessPendingUpdatesForView(nsView*, bool) /view/nsViewManager.cpp:375:22
        #47 0x7f9b7b436a3c in nsViewManager::ProcessPendingUpdates() /view/nsViewManager.cpp:948:5
        #48 0x7f9b7b7a3c2e in nsRefreshDriver::Tick(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp, nsRefreshDriver::IsExtraTick) /layout/base/nsRefreshDriver.cpp:2694:11
        #49 0x7f9b7b7ab9f0 in TickDriver /layout/base/nsRefreshDriver.cpp:368:13
        #50 0x7f9b7b7ab9f0 in mozilla::RefreshDriverTimer::TickRefreshDrivers(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp, nsTArray<RefPtr<nsRefreshDriver> >&) /layout/base/nsRefreshDriver.cpp:346:7
        #51 0x7f9b7b7ab8f3 in mozilla::RefreshDriverTimer::Tick(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) /layout/base/nsRefreshDriver.cpp:362:5
        #52 0x7f9b7b7ab7c0 in mozilla::VsyncRefreshDriverTimer::RunRefreshDrivers(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) /layout/base/nsRefreshDriver.cpp:896:5
        #53 0x7f9b7b7aae47 in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::TickRefreshDriver(mozilla::layers::BaseTransactionId<mozilla::VsyncIdType>, mozilla::TimeStamp) /layout/base/nsRefreshDriver.cpp:771:16
        #54 0x7f9b7b7aa493 in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::NotifyVsyncOnMainThread() /layout/base/nsRefreshDriver.cpp:650:7
        #55 0x7f9b7b7a9f8c in mozilla::VsyncRefreshDriverTimer::RefreshDriverVsyncObserver::NotifyVsync(mozilla::VsyncEvent const&) /layout/base/nsRefreshDriver.cpp:536:9
        #56 0x7f9b7acf4e4a in mozilla::dom::VsyncMainChild::RecvNotify(mozilla::VsyncEvent const&, float const&) /dom/ipc/VsyncMainChild.cpp:68:15
        #57 0x7f9b7af53a66 in mozilla::dom::PVsyncChild::OnMessageReceived(IPC::Message const&) /builds/worker/workspace/obj-build/ipc/ipdl/PVsyncChild.cpp:220:54
        #58 0x7f9b7741350c in mozilla::ipc::PBackgroundChild::OnMessageReceived(IPC::Message const&) /builds/worker/workspace/obj-build/ipc/ipdl/PBackgroundChild.cpp:6518:32
        #59 0x7f9b773a7311 in mozilla::ipc::MessageChannel::DispatchAsyncMessage(mozilla::ipc::ActorLifecycleProxy*, IPC::Message const&) /ipc/glue/MessageChannel.cpp:1707:25
        #60 0x7f9b773a4547 in mozilla::ipc::MessageChannel::DispatchMessage(mozilla::ipc::ActorLifecycleProxy*, IPC::Message&&) /ipc/glue/MessageChannel.cpp:1632:9
        #61 0x7f9b773a503d in mozilla::ipc::MessageChannel::RunMessage(mozilla::ipc::ActorLifecycleProxy*, mozilla::ipc::MessageChannel::MessageTask&) /ipc/glue/MessageChannel.cpp:1493:3
        #62 0x7f9b773a5bce in mozilla::ipc::MessageChannel::MessageTask::Run() /ipc/glue/MessageChannel.cpp:1528:14
        #63 0x7f9b7680e23e in mozilla::RunnableTask::Run() /xpcom/threads/TaskController.cpp:467:16
        #64 0x7f9b767e8a26 in mozilla::TaskController::DoExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /xpcom/threads/TaskController.cpp:780:26
        #65 0x7f9b767e76c3 in mozilla::TaskController::ExecuteNextTaskOnlyMainThreadInternal(mozilla::detail::BaseAutoLock<mozilla::Mutex&> const&) /xpcom/threads/TaskController.cpp:612:15
        #66 0x7f9b767e7933 in mozilla::TaskController::ProcessPendingMTTask(bool) /xpcom/threads/TaskController.cpp:390:36
        #67 0x7f9b76813366 in operator() /xpcom/threads/TaskController.cpp:124:37
        #68 0x7f9b76813366 in mozilla::detail::RunnableFunction<mozilla::TaskController::InitializeInternal()::$_0>::Run() /builds/worker/workspace/obj-build/dist/include/nsThreadUtils.h:531:5
        #69 0x7f9b767fd013 in nsThread::ProcessNextEvent(bool, bool*) /xpcom/threads/nsThread.cpp:1180:16
        #70 0x7f9b7680385d in NS_ProcessNextEvent(nsIThread*, bool) /xpcom/threads/nsThreadUtils.cpp:465:10
        #71 0x7f9b773accc6 in mozilla::ipc::MessagePump::Run(base::MessagePump::Delegate*) /ipc/glue/MessagePump.cpp:85:21
        #72 0x7f9b772ca4a7 in MessageLoop::RunInternal() /ipc/chromium/src/base/message_loop.cc:380:10
        #73 0x7f9b772ca3b2 in RunHandler /ipc/chromium/src/base/message_loop.cc:373:3
        #74 0x7f9b772ca3b2 in MessageLoop::Run() /ipc/chromium/src/base/message_loop.cc:355:3
        #75 0x7f9b7b49b8a8 in nsBaseAppShell::Run() /widget/nsBaseAppShell.cpp:137:27
        #76 0x7f9b7d5aa713 in XRE_RunAppShell() /toolkit/xre/nsEmbedFunctions.cpp:870:20
        #77 0x7f9b773adbba in mozilla::ipc::MessagePumpForChildProcess::Run(base::MessagePump::Delegate*) /ipc/glue/MessagePump.cpp:235:9
        #78 0x7f9b772ca4a7 in MessageLoop::RunInternal() /ipc/chromium/src/base/message_loop.cc:380:10
        #79 0x7f9b772ca3b2 in RunHandler /ipc/chromium/src/base/message_loop.cc:373:3
        #80 0x7f9b772ca3b2 in MessageLoop::Run() /ipc/chromium/src/base/message_loop.cc:355:3
        #81 0x7f9b7d5a9d49 in XRE_InitChildProcess(int, char**, XREChildData const*) /toolkit/xre/nsEmbedFunctions.cpp:729:34
        #82 0x557039c972f7 in content_process_main /browser/app/../../ipc/contentproc/plugin-container.cpp:57:28
        #83 0x557039c972f7 in main /browser/app/nsBrowserApp.cpp:327:18
        #84 0x7f9b8cc1a0b2 in __libc_start_main /build/glibc-sMfBJT/glibc-2.31/csu/../csu/libc-start.c:308:16
        #85 0x557039c72a7c in _start (/home/jkratzer/builds/mc-debug/firefox-bin+0x15a7c)
    
    UndefinedBehaviorSanitizer can not provide additional info.
    SUMMARY: UndefinedBehaviorSanitizer: SEGV /gfx/layers/wr/WebRenderCommandBuilder.cpp in mozilla::layers::WebRenderCommandBuilder::CreateWebRenderCommandsFromDisplayList(mozilla::nsDisplayList*, mozilla::nsDisplayItem*, mozilla::nsDisplayListBuilder*, mozilla::layers::StackingContextHelper const&, mozilla::wr::DisplayListBuilder&, mozilla::wr::IpcResourceUpdateQueue&, bool)
    ==3720950==ABORTING

Bugmon Analysis
Verified bug as reproducible on mozilla-central 20220418091627-0d591d3bc997.
The bug appears to have been introduced in the following build range:

Start: 846edaaa86a91c3bd761a5557bfc729cd89a4c25 (20210917212414)
End: 0cf96895f20cc52cfc3dca89f7b3f023028e7796 (20210917223817)
Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=846edaaa86a91c3bd761a5557bfc729cd89a4c25&tochange=0cf96895f20cc52cfc3dca89f7b3f023028e7796

Set release status flags based on info from the regressing bug 1729581

:botond, since you are the author of the regressor, bug 1729581, could you take a look?
For more information, please visit auto_nag documentation.

Hmm, can't seem to reproduce this one. Does it require any special prefs?

Botond, no. This crashes for me using a default configuration of mozilla-central rev 31346aa577d3 (built with --enable-debug --enable-fuzzing) on Ubuntu. Have you tried the STR in comment 0?

The severity field is not set for this bug.
:miko, could you have a look please?

For more information, please visit auto_nag documentation.

Bugmon was unable reproduce this issue.
Removing bugmon keyword as no further action possible. Please review the bug and re-add the keyword for further analysis.

A change to the Taskcluster build definitions over the weekend caused Bugmon to fail when reproducing issues. This issue has been corrected. Re-enabling bugmon.