def find_python_matches(
    identifier: str,
    requirements: Mapping[str, Iterator[Requirement]],
) -> Iterable[Candidate]:
    """All requires-python except for the first one(must come from the project)
    must be superset of the first one.
    """
    python_reqs = cast(Iterator[PythonRequirement], iter(requirements[identifier]))
    project_req = next(python_reqs)
    python_specs = cast(Iterator[PySpecSet], (req.specifier for req in python_reqs))
    if all(spec.is_superset(project_req.specifier or "") for spec in python_specs):
        return [project_req.as_candidate()]
    else:
        # There is a conflict, no match is found.
        return []
All requires-python except for the first one(must come from the project)
    must be superset of the first one.
    
src/pdm/resolver/python.py