python base64 decode incorrect padding错误解决方法

python的base64.decodestring方法做base64解码时报错：

traceback (most recent call last):
  file "/export/www/outofmemory.cn/controllers/user.py", line 136, in decryptpassword
    encryptpwd = base64.b64decode(encryptpwd)
  file "/usr/lib/python2.7/base64.py", line 76, in b64decode
    raise typeerror(msg)
typeerror: incorrect padding

这也算是python的一个坑吧，解决此问题的方法很简单，对base64解码的string补齐等号就可以了，如下代码：

        def decode_base64(data):
            """decode base64, padding being optional.

            :param data: base64 data as an ascii byte string
            :returns: the decoded byte string.

            """
            missing_padding = 4 - len(data) % 4
            if missing_padding:
                data += b'='* missing_padding
            return base64.decodestring(data)