capybara/virtualenv/lib/python2.7/site-packages/pip/req/req_set.py
def make_abstract_dist(req_to_install):
    """Factory to make an abstract dist object.

    Preconditions: Either an editable req with a source_dir, or satisfied_by or
    a wheel link, or a non-editable req with a source_dir.

    :return: A concrete DistAbstraction.
    """
    if req_to_install.editable:
        return IsSDist(req_to_install)
    elif req_to_install.link and req_to_install.link.is_wheel:
        return IsWheel(req_to_install)
    else:
        return IsSDist(req_to_install)
def make_abstract_dist(req_to_install):
    """Factory to make an abstract dist object.

    Preconditions: Either an editable req with a source_dir, or satisfied_by or
    a wheel link, or a non-editable req with a source_dir.

    :return: A concrete DistAbstraction.
    """
    if req_to_install.editable:
        return IsSDist(req_to_install)
    elif req_to_install.link and req_to_install.link.is_wheel:
        return IsWheel(req_to_install)
    else:
        return IsSDist(req_to_install)
Factory to make an abstract dist object.

    Preconditions: Either an editable req with a source_dir, or satisfied_by or
    a wheel link, or a non-editable req with a source_dir.

    :return: A concrete DistAbstraction.