The xmlrpc.client module has some trial-and-error logic at module import
time to figure out how to properly format years using strftime. There
have already been problems in the past with this code in Python (see
https://bugs.python.org/issue13305, which is still open), and Serenity
only adds to that.
This problem has been reported at https://bugs.python.org/issue45386, so
hopefully in time we won't need this patch anymore.