I'm using an embedded linux with a startup kernal time of 01/01/2010, with flask hosted site as a config tool. If the device doesn't have an internet connection (to update time from NTP), and they trigger TimeStampSigner.sign() function in itsdangerous.py, the int_to_byte assert fails as num is < 0.

I've not delved into why the logic expects the date to be greater then 2011, but it breaks it for me.