Prior to eggs, if I wanted to have debug and non-debug versions of an extension module available, I could build and install the extension twice and the modules would happily co-exist, for example:
$ python setup.py build install ... $ python-dbg setup.py build install ... $ .../site-packages/twisted/python$ ls *.so _epoll_d.so _epoll.so $ .../site-packages/twisted/python$
If I then ran a debug build of Python, the debug extension would be loaded. When I ran a normal build of Python, the non-debug extension would be loaded. However, with eggs, each new egg completely replaces the last egg. There seems to be no possibility for side-by-side builds. Am I overlooking a feature of eggs or of setuptools?