Modify Parser/asdl_c.py so that the __version__ number for Python/Python-ast.c is specified at the top of the file. Also add a note that Python/Python-ast.c needs to be committed separately after a change to the AST grammar to capture the revision number of the change (which is what __version__ is set to).

/* Return the full version string. */

#include "Python.h"

#include "patchlevel.h"

const char *
Py_GetVersion(void)
{
	static char version[250];
	PyOS_snprintf(version, sizeof(version), "%.80s (%.80s) %.80s", 
		      PY_VERSION, Py_GetBuildInfo(), Py_GetCompiler());
	return version;
}