bug#44942: 28.0.50; Emacs should print a backtrace on uncaught errors in batch mode

[Philipp Stephani <p.stephani2@gmail.com>]

Am So., 29. Nov. 2020 um 16:27 Uhr schrieb Philipp Stephani
<p.stephani2@gmail.com>:
>
> Am So., 29. Nov. 2020 um 11:48 Uhr schrieb Philipp Stephani
> <p.stephani2@gmail.com>:
> >
> >
> > $ emacs -Q -batch -eval '(progn (defun foo () (error "Boo")) (foo))'
> > Boo
> >
> > Emacs should print a backtrace here to make it possible to debug such
> > errors.  It's possible to force Emacs to print a backtrace by binding
> > `debug-on-error', however, that is incorrect because it changes the
> > meaning of `with-demoted-errors' and `condition-case-unless-debug',
> > causing code that would normally work to fail with an error.  Instead,
> > `signal' should print a backtrace if in batch mode and if it jumps to
> > the top-level error handler.  It looks like this logic could be
> > special-cased in signal_or_quit, similar to the debugger logic.
> >
>
>
> I've attached a patch.

Pushed to master as commit 40e11743ca.