Message 318330 - Python tracker

A crash in the test suite should be fixed, especially since we have protection against this crash (and a test that validates it).

In this case, apparently the stack allocation for each frame of r_object grew and now there isn't room for 2000 calls (the value of MAX_MARSHAL_STACK_DEPTH). This isn't really a robust way of handling it anyway, so I'll check out whether there's an easy way to safely probe the stack before recursing, otherwise we'll just have to cut the number a bit further.