Backport to Python 3.4 splitted in 3 patches:
* (1) timedelta_round_half_up_py34.patch, backport changeset 0eb8c182131e: "datetime.timedelta constructor now rounds microseconds to nearest with ties going away from zero (ROUND_HALF_UP)".
* (2) round_half_up.patch: add _PyTime_ROUND_HALF_UP rounding mode to the _PyTime API
* (3) fromtimestamp_round_half_up.patch, backport changeset bf634dfe076f: "fromtimestamp() and utcfromtimestamp() methods of datetime.datetime now round microseconds to nearest with ties going away from zero (ROUND_HALF_UP)"