It's unclear whether PyMarshal_XXX() are part of the public or private API.

They're named as if public, so I did a Bad Thing by changing
PyMarshal_ReadObjectFromFile() to suck up the remainder of the file in one
gulp:  anyone who counted on that leaving the file pointer merely at the
end of the next object would be screwed.  So restored
PyMarshal_ReadObjectFromFile() to its earlier state, renamed the new greedy
code to PyMarshal_ReadLastObjectFromFile(), and changed Python internals to
call the latter instead.

Python/pythonrun.c

@@ -936,7 +936,7 @@ run_pyc_file(FILE *fp, char *filename, PyObject *globals, PyObject *locals)
 		return NULL;
 	}
 	(void) PyMarshal_ReadLongFromFile(fp);
-	v = PyMarshal_ReadObjectFromFile(fp);
+	v = PyMarshal_ReadLastObjectFromFile(fp);
 	fclose(fp);
 	if (v == NULL || !PyCode_Check(v)) {
 		Py_XDECREF(v);