python获取下个月1号

old = datetime.datetime(2016, 12, 30, 13, 56, 51)
new = datetime.datetime(old.year + (old.month==12), old.month == 12 or old.month + 1, 1, 6, 0, 0)

参考：http://www.cnblogs.com/symons1992/p/5944445.html