merge: move the filtering of ambiguous files to a dedicated function
I have multiple reasons:
- The body of `_update` is way too long
- This adds typing which will help our tooling and brains understand this
code more easily
- This function will get more nested and complex in the next patch
I've taken the liberty of rewrapping and typo-passing the docstring.
#include <Python.h>
#if PY_MAJOR_VERSION >= 3
#define PYCODETYPE PyObject
#else
#define PYCODETYPE PyCodeObject
#endif
namespace contrib
{
void initpy(const char *cselfpath);
PyObject *pyglobals();
} /* namespace contrib */