bug#55743: 28.1.50; No directory error in comp-run-async-workers

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Date: Tue, 31 May 2022 20:31:36 +0300
> 
> So here are two problems: why completion sets default-directory to 
> non-existent dir,

That's the real problem.

> and why comp-run-async-workers tries to run a process in such arbitrary 
> invalid dirs.

It is not comp-run-async-workers that does it, it's the low-level
infrastructure in subroutines of make-process: it makes sure the
directory in which the process will run is valid, and if it isn't
signals an error.