Automatically do --no-use-pep517 builds, even without wheel

[stefanor]

In #13330 I removed the command line argument check for this, but I hadn't realized that there were also heuristics that needed to be fixed.

[sbidoul]

I'm not sure we want to create additional churn in this area, since pep517 will soon be the only supported mode.

[sbidoul]

Also, if the setuptools version is old (not that old) and wheel is not installed, bdist_wheel will fail, so that would be a new failure mode.

So let's not do this.

[stefanor]

Makes sense. I'd come to this, because I was updating (python-cffi/cffi#165) cffi's testsuite to handle the latest virtualenv without wheel (pypa/virtualenv#2868).

The test suite was expecting a non-pep517 build, even though it wasn't explicitly asking for one, and it took me embarrassingly long to figure out that I'd missed this bit of logic in #13330.

[sbidoul]

I'm curious why you need --no-use-pep517. Perhaps you just need --no-build-isolation?

[stefanor]

Ah yes, that works.

I went with --no-use-pep517 as that is what it was doing before, but indeed the issue is the isolation.