Python 3 can't handle dates.

python_dates.py

from datetime import datetime
now = datetime.utcnow()
t = now.timestamp()
t2 = datetime.utcfromtimestamp(t)
assert now == t2, 'Why no work?'

$ python3.5 python3_dates.py 
Traceback (most recent call last):
  File "python3_dates.py", line 5, in <module>
    assert now == t2, 'Why no work?'
AssertionError: Why no work?

$ python3.4 python3_dates.py 
Traceback (most recent call last):
  File "python3_dates.py", line 5, in <module>
    assert now == t2, 'Why no work?'
AssertionError: Why no work?

$ python3.3 python3_dates.py 
Traceback (most recent call last):
  File "python3_dates.py", line 5, in <module>
    assert now == t2, 'Why no work?'
AssertionError: Why no work?

So during the .timestamp() operation, it is interpreting the datetime as in my local time zone, because the utcnow() call is not clever enough to attach a UTC time zone to the value it returns?

Its actually even simpler, its just a rounding bug. Its losing precision during one of the calls (I'm not sure which one). The great thing is they actually did finally fix it on Friday so whenever the next release is I should finally be able to rip out all my custom date code :)

http://bugs.python.org/issue23517