'Set revision property to string value of integer *value*.'

@revision_number.setter
def revision_number(self, value):

    if ((not isinstance(value, int)) or (value < 1)):
        tmpl = u"revision    property    requires    positive    int,    got    '%s'"
        raise ValueError((tmpl % value))
    revision = self.get_or_add_revision()
    revision.text = str(value)
