'Do a rollover, as described in __init__().'

def doRollover(self):

    if (self.maxBytes <= 0):
        return
    if (not (self.stream.tell() >= self.maxBytes)):
        return
    self.stream.close()
    if (self.backupCount > 0):
        for i in range((self.backupCount - 1), 0, (-1)):
            sfn = ('%s.%d' % (self.baseFilename, i))
            dfn = ('%s.%d' % (self.baseFilename, (i + 1)))
            if os.path.exists(sfn):
                self.removeAndRename(sfn, dfn)
        dfn = (self.baseFilename + '.1')
        self.removeAndRename(self.baseFilename, dfn)
    self.stream = open(self.baseFilename, 'w')
