Removing the html extra dependency should be considered a breaking change

[mdellweg]

f3ef2e9 introduced a regression by breaking every dependent specifying tablib[html].
Assuming this project does semver (did not find a trace of that in the docs), this should be considered a breaking change unfit for y-releases.
I think the proper way solving this is keeping the "html" optional requirements group and just empty it until the next major release.

[hugovk]

So add an empty html = [] extra, and delete it in the next major release?

That sounds reasonable, would you like to open a PR?

[hugovk]

By the way, I get a warning not an error:

❯ pip install "tablib[html]"
Collecting tablib[html]
  Using cached tablib-3.6.0-py3-none-any.whl.metadata (3.7 kB)
WARNING: tablib 3.6.0 does not provide the extra 'html'
Using cached tablib-3.6.0-py3-none-any.whl (47 kB)
Installing collected packages: tablib
Successfully installed tablib-3.6.0

How exactly is it a breaking change? When turning warnings into errors?

I'm still fine with fixing this, but maybe it's less clearly a breaking change.

[mdellweg]

OK fair, I did assume.
I know we consume it via requireing django-import-export and that fails with pkg_resources.UnknownExtra: tablib 3.6.0 has no such extra feature 'html'.
Let me experiment.

[mdellweg]

OK, weird:

• Direct install of tablib[html] issues the warning you mentioned.
• Consecutive install of django-import-export downgrades tablib to 3.5.0.
• Direct install of django-import-export selects tablib 3.5.0.

There must be more going on in the dependency solver when more packages are requested. Or the version of pip is just different... But still I'd say the above already fails at the principle of least surprise. And I could swear I once read that one is not supposed to completely remove a optional deps key (cannot find it anymore).

[reproducer; probably not minimal, but 10 out of 10 reproducable] https://github.com/pulp/pulp_ansible/actions/runs/8540040263/job/23396219288?pr=1803#step:10:928