Currently, the dependency chain of python stuff is created before cython invocations.

But cython can be used to compile a python file to native code as a .so file. This file will be loaded before the same-content-but-nonnative .py file.

This currently leads to the problem that if some python file depends on another python file that will be compiled, the compilation depends on a compiled file, which is a circle.
#435 happened because of this and the root cause still needs a fix.

The easiest fix is probably checking if a .so-file has a same-named .py file in the same folder, then the build can simply continue.

After you can reproduce this problem, this should be done in openage/codegen/codegen.py.

Related: #442 (the .so is not removed)