glxinfo|grep OpenGL
OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) HD Graphics 5500 (Broadwell GT2)
OpenGL core profile version string: 4.3 (Core Profile) Mesa 12.0.3
OpenGL core profile shading language version string: 4.30
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 12.0.3
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.1 Mesa 12.0.3
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.10
OpenGL ES profile extensions:

changes the value returned by glGetString(GL_VERSION) and possibly the GL API type.

MESA_GL_VERSION_OVERRIDE=3.3 glxinfo | grep OpenGL

OpenGL version string: 3.3 (Core Profile) Mesa 12.0.3
OpenGL shading language version string: 3.30

MESA_GL_VERSION_OVERRIDE=4.3 command