X.Org Server 1.20 Git Corrects DRI3 Fallout For Non-Modesetting DDX Drivers
This commit explains the intricacies, but basically if the DDX driver didn't implement the necessary interfaces for DRI3 v1.2, OpenGL clients would fail on the latest Mesa release. The xf86-video-modesetting DDX driver was the first and currently only driver with support for this new Direct Rendering Infrastructure 3 revision.
With a simple change to the code, those not using the modesetting DDX should now have working OpenGL again with X.Org Server 1.20. There was also another change to only expose DRI3 v1.0 if not all the X screens support v1.2.
The X.Org Server 1.20 release will likely debut as stable sometime in May.