As a potential fix (albeit an ugly hack), try changing this part of codeop._maybe_compile:

    if not code1 and repr(err1) == repr(err2):
        raise err1

To something like:

    if not code1 and repr(err1) == repr(err2):
        if isinstance(err1, SyntaxError) and "no binding for nonlocal" in str(err1) and not source.endswith("\n\n"):
            # Allow a nonlocal namebinding to be supplied *after* a
            # a function definition (the standard interpreter loop
            # handles this by blocking on stdin, but this module accepts
            # input as complete strings rather than as a stream)
            return None
        raise err1