When you call datetime.datetime.utcnow() you get back a naive datetime
object. But why? You asked for UTC as the timezone based on what method
call you made. And UTC is a very concrete timezone that never changes.

It would be nice to have a concrete UTC tzinfo class that utcnow() uses
so that at least those datetime instances are non-naive.

If people have no issues with making this happen I will write the code
for the concrete UTC tzinfo instance and make the appropriate changes to
utcnow().