def clean_nginx_git_tag(tag):
    """
    Return a cleaned ``version`` string from an nginx git tag.

    Nginx tags git release as in `release-1.2.3`
    This removes the the `release-` prefix.

    For example:
    >>> clean_nginx_git_tag("release-1.2.3") == "1.2.3"
    True
    >>> clean_nginx_git_tag("1.2.3") == "1.2.3"
    True
    """
    if tag.startswith("release-"):
        _, _, tag = tag.partition("release-")
    return tag