Rescaling Normals

Normals can be automatically rescaled, to be unit length.

glEnable(GL_NORMALIZE)

Computes length of each normal, and forces it to be 1.

glEnable(GL_RESCALE_NORMAL)

Resizes each normal, based on the scale factor of the ModelView transformation.
Faster, but won't work with non-uniform scaling.

Note: GL_RESCALE_NORMAL is part of OpenGL 1.2. PyOpenGL only provides an OpenGL 1.1 interface. As long as your underlying driver is 1.2 or later, you can define the constant yourself:
        GL_RESCALE_NORMAL = 0x803A