bug#62004: 30.0.50; comp-run-async-workers failure when default-directory deleted

[Eli Zaretskii <eliz@gnu.org>]

> From: Andrea Corallo <akrl@sdf.org>
> Cc: No Wayman <iarchivedmywholelife@gmail.com>,  62004@debbugs.gnu.org
> Date: Tue, 07 Mar 2023 11:16:40 +0000
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Andrea, any ideas?  How come we never ran into this issue until now?
> 
> I guess it's a very unlikely condition that was never
> encountered/reported.
> 
> > Is the default-directory value when native compilation is forked
> > somehow derived from the directory of the file being compiled?
> 
> If it is is not evident to me why.  We spawan something of this kind
> 
> /pathtoemacs/emacs -Q -batch -l /tmp/emacs-async-comp-something.el
> 
> where emacs-async-comp-something.el contains the actual setup (where we
> don't touch default-directory) and compilation command.
> 
> I'm probably missing something ATM.

Well, maybe we should bind the variable to be on the safe side?  What
if we bind it to the directory where we write that
emacs-async-comp-something.el file?