Xorg suddenly crashed with SIGABRT in OsAbort()

[wvengen]

Just having upgraded from 15.04 to 15.10 beta, I had my first Xorg crash (intel chipset). Was just using the system when it happened. External display attached.

ProblemType: Crash
DistroRelease: Ubuntu 15.10
Package: xserver-xorg-core 2:1.17.2-1ubuntu9
ProcVersionSignature: Ubuntu 4.2.0-14.16-generic 4.2.2
Uname: Linux 4.2.0-14-generic x86_64
NonfreeKernelModules: wl
.tmp.unity.support.test.0:

ApportVersion: 2.19-0ubuntu1
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: GNOME
Date: Wed Oct 7 10:48:35 2015
DistUpgraded: 2015-10-07 10:17:39,505 DEBUG enabling apt cron job
DistroCodename: wily
DistroVariant: ubuntu
ExecutablePath: /usr/bin/Xorg
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation Haswell-ULT Integrated Graphics Controller [8086:0a2e] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: Apple Inc. Device [106b:011a]
InstallationDate: Installed on 2014-10-17 (355 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Alpha amd64 (20141016)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 05ac:025a Apple, Inc.
 Bus 001 Device 006: ID 05ac:8289 Apple, Inc.
 Bus 001 Device 002: ID 0a5c:4500 Broadcom Corp. BCM2046B1 USB 2.0 Hub (part of BCM2046 Bluetooth)
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Apple Inc. MacBookPro11,1
ProcCmdline: /usr/bin/X vt7 -displayfd 3 -auth /run/user/117/gdm/Xauthority -nolisten tcp -background none -noreset -keeptty -verbose 3
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-14-generic.efi.signed root=UUID=3b2baf5c-6d36-42d2-84a3-5ab5c08c6a6f ro rootflags=data=writeback libata.force=noncq i915.enable_ips=0 quiet splash vt.handoff=7
Signal: 6
SourcePackage: xorg-server
StacktraceTop:
 OsAbort ()
 FatalError ()
 ?? ()
 xf86CloseConsole ()
 ddxGiveUp ()
Title: Xorg crashed with SIGABRT in OsAbort()
UpgradeStatus: Upgraded to wily on 2015-10-07 (0 days ago)
UserGroups:

dmi.bios.date: 02/12/2014
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBP111.88Z.0138.B07.1402121134
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-189A3D4F975D5FFC
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookPro11,1
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-189A3D4F975D5FFC
dmi.modalias: dmi:bvnAppleInc.:bvrMBP111.88Z.0138.B07.1402121134:bd02/12/2014:svnAppleInc.:pnMacBookPro11,1:pvr1.0:rvnAppleInc.:rnMac-189A3D4F975D5FFC:rvrMacBookPro11,1:cvnAppleInc.:ct10:cvrMac-189A3D4F975D5FFC:
dmi.product.name: MacBookPro11,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
version.compiz: compiz N/A
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.64-1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.0.0-1ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.0.0-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.17.2-1ubuntu9
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.5.0+git20150819-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20150808-0ubuntu3
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.11-1ubuntu3
xserver.bootTime: Wed Oct 7 12:58:12 2015
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 40984
 vendor APP
xserver.version: 2:1.17.2-1ubuntu9

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #1237904, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.