Allow towncrier to traverse back up directories looking for the configuration file

[SmileyChris]

Description

Fixes #433

Checklist

• Make sure changes are covered by existing or new tests.
• For at least one Python version, make sure local test run is green.
• Create a file in src/towncrier/newsfragments/. Describe your
  change and include important information. Your change will be included in the public release notes.
• Make sure all GitHub Actions checks are green (they are automatically checking all of the above).
• Ensure docs/tutorial.rst is still up-to-date.

[adiroiban]

Many thanks for the changes.

They look good.

I left a few minor inline comments.

The major comment is about the missing test for the case in which the config file was not found, even when traversing the whole tree.

I think that we should have such a test before merging this.

Thanks again!

[adiroiban]

I think that this should be private.

I know that this is from _settings.load , but I think that we should make it explicit that we don't want to expose this as a public API.

Also, there are a lot of branches here,
so I think that it would help to add an explicit comment for this branch.

With the missing docstring for the load_config_from_options it's a bit hard to understand the purpose of this function.

Can we have something like this.

It lools like a bit of duplication between
traverse_for_config and these following lines

base_directory = os.path.abspath(directory)
config = load_config(base_directory)

maybe have something like this

    if config_path is None:
        return _traverse_for_config(directory)

[SmileyChris]

I don't think there's any assumption that non underscored methods become automatically part of a public API is there? If people want to shoot themselves in the foot, let em 🤠

[SmileyChris]

I've added a docstring and some comments to explain the different branches (I don't like the complexity of the towncrier's loading, but I'm not going to rewrite it just for this addition)

[SmileyChris]

Actually, I see what you're getting at with the branching logic now. I've simplified it (and added another test).

[adiroiban]

Thanks for the updates.

All good.

[adiroiban]

Thanks for the cleanup for load_config_from_options. Much appreciated.