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 时区的 zoneinfo 示例重现文档中记录的 datetime 比较和减法行为，并检查 datetime.datetime 排序和减法的入口点。将结果与 timestamp 排序以及文档中所述的语义进行比较；当行为和文档在 DST fold 情况下保持一致，并具备相关的回归测试覆盖时，即视为完成。