Hi Mathias.  There is a current proposal (http://www.python.org/dev/peps/pep-0432/) for improving interpreter startup.  So changes in this area are subject to extra caution.  The changes you are talking about are at least indirectly impacted by the proposal, though I expect they are more directly tied to what happens in site.py.

As to your proposal, aren't the embedding needs already addressed?  See http://docs.python.org/2/c-api/intro.html#embedding-python.  Is there some convention for keeping the site files adjacent to the SO/DLL that would warrant your proposed code?

p.s. this would be a new feature so it only applies to Python 3.4.