bug#47168: 28.0.50; Infinite recursion in project-root

[Stefan Monnier]

> Stefan, any chance there's a relatively non-dirty way we can check whether
> there is a non-default implementation for the generic function with given
> args, before calling it?

Not really, no.  We could refrain from providing a default
implementation, and instead add a method to `cl-no-next-method` or
something like that, but I'm not sure it would make much difference.

> That would allow us to break recursion.

But we could use some dynamically-scoped
`project--within-roots-fallback` variable to break such recursion ;-)


        Stefan