Confused on git commit tree about Lib/datetime.py

[Thomas Jollans]

On 01/08/18 12:49, Chris Angelico wrote:
> On Wed, Aug 1, 2018 at 8:40 PM, Thomas Jollans <tjol at tjol.eu> wrote:
>> On 01/08/18 05:16, Jeffrey Zhang wrote:
>>> I found a interesting issue when checking the Lib/datetime.py
>>> implementation in python3
>>>
>>> This patch is introduced by cf86e368ebd17e10f68306ebad314eea31daaa1e [0].
>>> But if you
>>> check the github page[0], or using git tag --contains, you will find
>>> v2.7.x
>>> includes this commit too.
>>>
>>> $ git tag --contains cf86e368ebd17e10f68306ebad314eea31daaa1e
>>> 3.2
>>> v2.7.10
>>> v2.7.10rc1
>>> v2.7.11
>>> v2.7.11rc1
>>> ...
>>>
>>> whereas, if you check the v2.7.x code base, nothing is found
>>>
>>> $ git log v2.7.4 -- Lib/datetime.py
>>> <nothing here>
>>>
>>> I guess it maybe a git tool bug, or the commit tree is messed up. Is there
>>> any guys could explain this
>>> situation?
>>>
>>> [0]
>>>
>>> https://github.com/python/cpython/commit/cf86e368ebd17e10f68306ebad314eea31daaa1e
>>>
>> There are some crazy merges in the repository history, that are easy to see
>> with gitk (and not so easy to see with github or the command-line porcelain)
>>
>> In this case, it appears that d26b658f1433a28b611906c078f47bc804a63dd1, in
>> the mercurial days, cherry-picked a patch from the 3.2 branch at
>> f8b9dfd9a1a3d611d43e3c3ef8031fed96c8dd25.
>>
>> I don't know why the git tools don't find this by themselves. I suppose this
>> is a quirk of the hg-git transition and the different ways hg and git have
>> of doing things.
> I'm not sure what you're expecting them to find. They find that the
> commit in question is part of the 2.7 branch, so every parent of it is
> also part of the 2.7 branch. They are correctly reporting it. The
> commit is a bit weird, but the tools are faithfully reporting the
> weirdness.
>
> ChrisA

That's not the big I'm confused about. I (like Jeffrey) would have expected

git log v2.7.4 -- Lib/datetime.py

to show something. But right now I'm not sure that ever shows anything for deleted files, so there's that.

Thomas