def fixPickupMeasure(partObject):
    """Fix a pickup measure if any.

    We determine a pickup measure by being measure 0 and not having an RN
    object at the beginning.

    Demonstration: an otherwise incorrect part

    >>> p = stream.Part()
    >>> m0 = stream.Measure()
    >>> m0.number = 0
    >>> k0 = key.Key('G')
    >>> m0.insert(0, k0)
    >>> m0.insert(0, meter.TimeSignature('4/4'))
    >>> m0.insert(2, roman.RomanNumeral('V', k0))
    >>> m1 = stream.Measure()
    >>> m1.number = 1
    >>> m2 = stream.Measure()
    >>> m2.number = 2
    >>> p.insert(0, m0)
    >>> p.insert(4, m1)
    >>> p.insert(8, m2)

    After running fixPickupMeasure()

    >>> romanText.translate.fixPickupMeasure(p)
    >>> p.show('text')
    {0.0} <music21.stream.Measure 0 offset=0.0>
        {0.0} <music21.key.Key of G major>
        {0.0} <music21.meter.TimeSignature 4/4>
        {0.0} <music21.roman.RomanNumeral V in G major>
    {2.0} <music21.stream.Measure 1 offset=2.0>
    <BLANKLINE>
    {6.0} <music21.stream.Measure 2 offset=6.0>
    <BLANKLINE>
    >>> m0.paddingLeft
    2.0
    """
    m0 = partObject.measure(0)
    if m0 is None:
        return
    rnObjects = m0.getElementsByClass('RomanNumeral')
    if not rnObjects:
        return
    if rnObjects[0].offset == 0:
        return
    newPadding = rnObjects[0].offset
    for el in m0:
        if el.offset < newPadding:
            pass
        else:
            el.offset = el.offset - newPadding
    m0.paddingLeft = newPadding
    for el in partObject:
        if el.offset > 0:
            el.offset -= newPadding
