Python loading system numpy in preference to MacPorts version (Lion)

[jamie@…]

I'm having an issue where python scripts are loading the system numpy version instead of the MacPorts compiled version, this leads to the following error message:

RuntimeError: module compiled against API version 6 but this version of numpy is 4

and in some cases (e.g. scripts that use matplotlib) causes crashes.

This has only started occurring on my system since I upgraded to OS X Lion.

The fix so far seems to be to add the following code to the top of each script before loading numpy:

sys.path.reverse()

but this is extremely kludgy fix, and I never had to previously do this. My PYTHONPATH variable points to my local python repository and to the MacPorts site-packages directory only. Is there somewhere else I can tell python to stop loading stuff from /System/Library/Frameworks/Python.framework?