Another py3 anecdote. We have a service with back-ends. So, on py2 it logs "waiting for [('188.8.131.52:5', 'sdb1')]". On py3 it logs " waiting for <zip object at 0x7fbf55e d7708>", which is useless for a sysadmin.
@kazriko Well yea, throwing list() on all sort of objects is the way to go in py3. One subtle thing though, I have to do u=list(zip(x, y)) instead of logger(list(u)), because by the time we're ready to log an error, contents of the zip are already consumed, so yet again the log is useless then.