xinit can't start

[Qiang Yu]

xinit can't start from command line while startx and lightdm is OK.

Reproduce:
1. setup to boot into command line by
$ sudo systemctl set-default multi-user.target
2. reboot into command line
3. login and tart xinit by
$ xinit

The error log is
[ 237.119] (EE) xf86OpenConsole: Cannot open /dev/tty0 (No such file or directory)

But this way the xinit is OK
xinit -- /usr/bin/X :0 vt1 -nolisten

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xinit 1.3.4-3
ProcVersionSignature: Ubuntu 4.4.0-8.23-generic 4.4.2
Uname: Linux 4.4.0-8-generic x86_64
.tmp.unity.support.test.0:

ApportVersion: 2.20-0ubuntu3
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Tue Mar 8 09:57:43 2016
DistUpgraded: Fresh install
DistroCodename: xenial
DistroVariant: ubuntu
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Hawaii XT [Radeon R9 290X] [1002:67b0] (prog-if 00 [VGA controller])
   Subsystem: Advanced Micro Devices, Inc. [AMD/ATI] Hawaii XT [Radeon R9 290X] [1002:0b00]
InstallationDate: Installed on 2016-03-01 (6 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160228)
MachineType: Gigabyte Technology Co., Ltd. X58A-UD3R
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-8-generic root=UUID=c137e0c1-ad99-47f4-acf5-e7f4792afa9e ro quiet splash vt.handoff=7
SourcePackage: xinit
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/23/2010
dmi.bios.vendor: Award Software International, Inc.
dmi.bios.version: FE
dmi.board.name: X58A-UD3R
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrFE:bd12/23/2010:svnGigabyteTechnologyCo.,Ltd.:pnX58A-UD3R:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnX58A-UD3R:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr:
dmi.product.name: X58A-UD3R
dmi.sys.vendor: Gigabyte Technology Co., Ltd.
version.compiz: compiz 1:0.9.12.2+16.04.20160209-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.67-1
version.libgl1-mesa-dri: libgl1-mesa-dri 11.1.2-1ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 11.1.2-1ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.17.3-2ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.9.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.6.1-1ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160218-1ubuntu2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.12-1build1
xserver.bootTime: Tue Mar 8 09:46:59 2016
xserver.configfile: default
xserver.errors: systemd-logind: failed to get session: PID 893 does not belong to any known session
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.17.3-2ubuntu4
xserver.video_driver: radeon