Be more helpful when pyproject.toml is missing

[nbraud]

• Emit an error referring to PEP 517 and to the buildsystem's documentation.
• When the setup.py style is detected, suggest a basic pyproject.toml.
• Improve bork's error display, to ensure error messages aren't pushed off-screen by a backtrace.

[nbraud]

I'm very sorry for how the setuptools error message is laid out, I just couldn't find a way to both:

• have it be readable in the console (esp. with the code block indented) ;
• have it be readable in the source code ;
• have it be indented in a Pythonic way.

[duckinator]

This looks good to me. The indentation weirdness is basically expected unless you use textwrap.dedent, but that might be overkill.

Do you want to try to figure out improving the error display here, or defer that to a follow-up PR?

If you're okay with this as-is, I'm okay with it being merged (as long as an issue exists about improving error output). If you want to work on it more first, lmk if you need help/feedback/someone to bounce ideas off. 👍

[nbraud]

Do you want to try to figure out improving the error display here, or defer that to a follow-up PR?

If you're okay with this as-is, I'm okay with it being merged (as long as an issue exists about improving error output). If you want to work on it more first, lmk if you need help/feedback/someone to bounce ideas off. +1

I'm not sure TBH? Maybe let's merge this and make an issue to bounce ideas in?

I'm honestly very unsure how to do this, what the end result should look, ...

[nbraud]

bors r=duckinator

[bors]

Build succeeded:

• CI success