System Environment:
--------------------------
Platform: Broadwell
Libdrm:		(master)libdrm-2.4.53-6-gd4083dc762a2974c35ecd16be995272bbb6d57b4
Mesa:		(master)34a68345e228b7cbc1bc6909704a89c08bf5368e
Xserver:	(master)xorg-server-1.15.99.902-47-ge924034269532979f1e88947ee9c33d30461edae
Xf86_video_intel:(master)2.99.911-94-gbb5b21e34f6cbe44a249e566471754b45c500e60
Libva:		(staging)8577efbd3b1d4e8f113f78cf13d2182aa681b738
Libva_intel_driver:(staging)42258e128f19b93aa102672d5f61eb73d9f9808f
Kernel:	(drm-intel-nightly)1e771b84e47085ef9b6efea1321e7cb5a8b2c065

Bug detailed description:
-----------------------------
It fails on Broadwell with Mesa master branch, but works well on Haswell.
output:
libGL: screen 0 does not appear to be DRI3 capable
libGL: pci id for fd 4: 8086:1616, driver i965
libGL: OpenDriver: trying /opt/X11R7/lib/dri/i965_dri.so
Probe color at (0,50)
  Expected: 0.500000 0.500000 0.500000 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 0 1
Probe color at (0,100)
  Expected: 0.333333 0.333333 0.333333 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 0 2
Probe color at (75,0)
  Expected: 0.250000 0.250000 0.250000 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 1 0
Probe color at (75,50)
  Expected: 0.200000 0.200000 0.200000 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 1 1
Probe color at (75,100)
  Expected: 0.166667 0.166667 0.166667 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 1 2
PIGLIT:subtest {'Render multi-scissor rectangles' : 'fail'}
Probe color at (0,50)
  Expected: 0.500000 0.500000 0.500000 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 0 1
Probe color at (0,100)
  Expected: 0.333333 0.333333 0.333333 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 0 2
Probe color at (75,0)
  Expected: 0.250000 0.250000 0.250000 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 1 0
Probe color at (75,50)
  Expected: 0.200000 0.200000 0.200000 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 1 1
Probe color at (75,100)
  Expected: 0.166667 0.166667 0.166667 1.000000
  Observed: 0.000000 0.000000 0.000000 0.000000
Wrong color for viewport i,j 1 2
PIGLIT:subtest {'Render multi-viewport scissor test' : 'fail'}
PIGLIT: {'result': 'fail' }


Reproduce steps:
----------------------------
1. xinit
2. ./bin/arb_viewport_array-render-scissor -fbo -auto