Alessandro, did you try running the test suite? It is broken for me. One of the bugs is that it now omits zero hours, minutes, and seconds in addition to microseconds. (Kind of the reverse of what the bug was originally about :).

Other failures look like this:

======================================================================
ERROR: test_isoformat (test.datetimetester.TestDateTime)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/media/disk/home/proj/python/cpython/Lib/test/datetimetester.py", line 1560, in test_isoformat
    timespec_error = self.time()
AttributeError: 'TestDateTime_Pure' object has no attribute 'time'

I will leave some review comments.