Bugs after upgrade

Hello,
     dunno if this is the proper place to ask this kind of question, but 
before I file a bug, I'd like to actually clarify if it IS a bug.

     So - after upgrading my system (Arch), the rendering in my pet 
project is pretty broken. I am pretty certain I didn't use any 
driver-specific or undefined behaviors, and I think the issue has to do 
with stencil function which I use mainly to optimize deferred rendering 
and isolate geometry and skybox.
I noticed that Changelog has some changes regarding access of reference 
value for stencil tests.

     I can describe the errors, but I think its best you see for yourself:
Before update - 
https://dl.dropboxusercontent.com/u/80655/possible_bugs/Screenshot%20from%202013-08-16%2011%3A21%3A54.png

After update - 
https://dl.dropboxusercontent.com/u/80655/possible_bugs/Screenshot%20from%202013-08-31%2018%3A02%3A21.png


Shortly: skybox is missing, SSAO is inverted (?), and black artifacts 
make it difficult to figure out if errors have to do with spotlights or 
some weird stenciling/depth tests again.
My package manager log explained how to configure X11 to fall back to 
UXA acceleration instead of new SNA - but that didn't fix anything either.

I can't stress enough that I _did not_ change any rendering code in the 
meantime, as a matter of fact I checked out version from 2013/08/16 and 
tried it out, and ran into same issues; therefore, I am fairly certain 
that either a bug was introduced, or I was (unknowingly) using 
driver-specific behavior.
That being said, I am not using any obscure GL features, only very 
standard things (floating point textures, DepthStencil fb attachments 
and such).


My working machine is a laptop with Intel's GPU, lspci:

00:00.0 Host bridge: Intel Corporation Core Processor DRAM Controller 
(rev 12)
00:02.0 VGA compatible controller: Intel Corporation Core Processor 
Integrated Graphics Controller (rev 12)
00:16.0 Communication controller: Intel Corporation 5 Series/3400 Series 
Chipset HECI Controller (rev 06)
00:1a.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset 
USB2 Enhanced Host Controller (rev 06)
00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset 
High Definition Audio (rev 06)
00:1c.0 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI 
Express Root Port 1 (rev 06)
00:1c.1 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI 
Express Root Port 2 (rev 06)
00:1c.2 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI 
Express Root Port 3 (rev 06)
00:1c.4 PCI bridge: Intel Corporation 5 Series/3400 Series Chipset PCI 
Express Root Port 5 (rev 06)
00:1d.0 USB controller: Intel Corporation 5 Series/3400 Series Chipset 
USB2 Enhanced Host Controller (rev 06)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev a6)
00:1f.0 ISA bridge: Intel Corporation Mobile 5 Series Chipset LPC 
Interface Controller (rev 06)
00:1f.2 SATA controller: Intel Corporation 5 Series/3400 Series Chipset 
4 port SATA AHCI Controller (rev 06)
00:1f.3 SMBus: Intel Corporation 5 Series/3400 Series Chipset SMBus 
Controller (rev 06)
00:1f.6 Signal processing controller: Intel Corporation 5 Series/3400 
Series Chipset Thermal Subsystem (rev 06)
02:00.0 Network controller: Qualcomm Atheros AR9285 Wireless Network 
Adapter (PCI-Express) (rev 01)
05:00.0 Ethernet controller: Qualcomm Atheros AR8131 Gigabit Ethernet 
(rev c0)
3f:00.0 Host bridge: Intel Corporation Core Processor QuickPath 
Architecture Generic Non-core Registers (rev 02)
3f:00.1 Host bridge: Intel Corporation Core Processor QuickPath 
Architecture System Address Decoder (rev 02)
3f:02.0 Host bridge: Intel Corporation Core Processor QPI Link 0 (rev 02)
3f:02.1 Host bridge: Intel Corporation Core Processor QPI Physical 0 
(rev 02)
3f:02.2 Host bridge: Intel Corporation Core Processor Reserved (rev 02)
3f:02.3 Host bridge: Intel Corporation Core Processor Reserved (rev 02)



If anybody can give me a shout regarding this, I'd be most thankful.
Cheers.