def render_pep440_branch(pieces):
    """TAG[[.dev0]+DISTANCE.gHEX[.dirty]] .

    The ".dev0" means not master branch. Note that .dev0 sorts backwards
    (a feature branch will appear "older" than the master branch).

    Exceptions:
    1: no tags. 0[.dev0]+untagged.DISTANCE.gHEX[.dirty]
    """
    if pieces["closest-tag"]:
        rendered = pieces["closest-tag"]
        if pieces["distance"] or pieces["dirty"]:
            if pieces["branch"] != "master":
                rendered += ".dev0"
            rendered += plus_or_dot(pieces)
            rendered += "%d.g%s" % (pieces["distance"], pieces["short"])
            if pieces["dirty"]:
                rendered += ".dirty"
    else:
        # exception #1
        rendered = "0"
        if pieces["branch"] != "master":
            rendered += ".dev0"
        rendered += "+untagged.%d.g%s" % (pieces["distance"],
                                          pieces["short"])
        if pieces["dirty"]:
            rendered += ".dirty"
    return rendered
TAG[[.dev0]+DISTANCE.gHEX[.dirty]] .

    The ".dev0" means not master branch. Note that .dev0 sorts backwards
    (a feature branch will appear "older" than the master branch).

    Exceptions:
    1: no tags. 0[.dev0]+untagged.DISTANCE.gHEX[.dirty]
    
binderhub/_version.py