When installing PyOpenGL-3.0.0a5 from source against a Python-2.4 install,
downloading and installing ctypes seems to be forced
(although unnecessary in the case ctypes is already installed).
This is apparently coming from setup.py:
if sys.hexversion < 0x2050000:
requirements.append( 'ctypes' )
(and could be fixed by having a try/except
around an 'import ctypes' to check for an available
ctypes for example).