These methods can be trivially supported in Mesa 7.6 without advertizing OpenGL 3.0. Nvidia and Ati binary drivers expose these methods even on 2.1 contexts - there's no reason why Mesa cannot do the same.
Edit: Digging around, I think this post is the root of the GL_VERSION issue. The first number in "1.4 (2.1 Mesa 7.0.1)" is the highest OpenGL version that can be officially supported under the current GLX implementation when using indirect rendering. Which means that I either hit a Mesa bug or was just plain lucky by only using supported methods.
Still, the whole confusion wouldn't even exist with glGetInteger(GL_[MAJOR|MINOR]).