In pkg_setup, pyopengl uses opengl-update to change the opengl implementation. This is incorrect behavior. If the ebuild does not complete, the user's opengl implementation is changed without the user's consent. Also, this breaks on any system without opengl-update (yes there are some, and yes it is valid to not have it and still have opengl functioning). Instead, the package should be patched to include the proper files it requires, rather than relying on the opengl symlinks.
vapier removed it.