[Distutils] A possible refactor/streamlining of PEP 517

[Donald Stufft]

One point of issue with the PEP as it currently stands: I would greatly prefer it if we had a sigil to differentiate from "can't build the sdist, please fall back" from "an error has occurred trying to build the sdist". This would allow flit to return something that's says it can't build a sdist inn the current tree but won't end up swallowing legit errors from trying to build a sdist. 

Sent from my iPhone

> On Jul 17, 2017, at 7:30 AM, Thomas Kluyver <thomas at kluyver.me.uk> wrote:
> 
> The
> important point for me is that an sdist is not a requirement for
> installing from source -  it's ok by me if it tries building an sdist
> first and then falls back to building a wheel directly.