With these 11 patches are all that's separating Mesa Git from hitting OpenGL 4.2 from OpenGL 4.0 for Haswell. Of course, Broadwell and newer has been at OpenGL 4.5 since Mesa 13.0.
These patches take care of the prep work and then enabling of ARB_vertex_attrib_64bit and ARB_shader_precision for Haswell, the remaining bits needed before seeing OpenGL 4.2. The patches come in at just under 200 lines of new code and is much less invasive than the big FP64 work that went in last week.
The other extensions needed for OpenGL 4.3/4.4/4.5 should already be enabled for Haswell, but there may need some tweaks and conformance testing before seeing these later GL4 versions. But don't get too excited about all this OpenGL 4 work considering that Haswell graphics aren't the fastest and these patches don't do anything to magically make an Intel IGP system a useful Linux gaming box.