astropy 0.2 tests write to site-packages for Python 3

I have astropy 0.2 installed on Mac via Macports and sudo in `/opt/local/`.
When I try to run the tests as a normal user (without sudo) it fails because of permission problems, I think when it tries to write to the site-packages directory ([full log](https://gist.github.com/cdeil/5019687)):
```
$ python3.2 -c 'import astropy; astropy.test()'
...
E   IOError: [Errno 13] Permission denied: '/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/astropy/config/tests/__pycache__/test_configs.cpython-32-PYTEST.pyc.37153'
___ ERROR collecting ../../opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/astropy/constants/tests/test_constant.py ___
...
E   IOError: [Errno 13] Permission denied: '/opt/local/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/astropy/wcs/tests/__pycache__/test_wcsprm.cpython-32-PYTEST.pyc.37153'
================================================================== 83 error in 6.01 seconds ==================================================================
```

I guess a user should be able to test a system-installed astropy?