datetime: Comparision and subtraction of datetime objects does not account for DST changes

Bug report

Bug description:

The documentation of datetime ordering predicates says both that "datetime1 is considered less than datetime2 when datetime1 precedes datetime2 in time, taking into account the time zone" but also "If both comparands are aware, and have the same tzinfo attribute, the tzinfo and fold attributes are ignored"

I believe that ignoring fold, though documented, is incorrect, and contradicts the earlier "precedes ... in time" explanation of what the expression dt1 < dt2 means. If avoiding a conversion to UTC is an important performance optimization, a possibility is to continue to avoid it provided that the fold= and tzinfo= values are the same in both comparands.

>>> from datetime import datetime
>>> import zoneinfo
>>> la = zoneinfo.ZoneInfo("America/Los_Angeles")
>>> t1 = datetime.fromtimestamp(1604221200.0, tz=la)
>>> t2 = datetime.fromtimestamp(1604217660.0, tz=la)
>>> t1 < t2
True
>>> t1.timestamp() < t2.timestamp()
False

Tested on: 3.13.5, 3.15.0a2

CPython versions tested on:

3.15

Operating systems tested on:

Linux

Linked PRs

• gh-146294

使用 America/Los_Angeles 時區的 zoneinfo 範例重現文件中記錄的 datetime 比較與減法行為，並檢查 datetime.datetime 排序與減法的進入點。將結果與 timestamp 排序以及文件中所述的語意進行比較；當行為與文件在 DST fold 情況下保持一致，並具備相關的回歸測試涵蓋率時，即視為完成。