bug#65267: 30.0.50; modifying debug-ignored-errors during startup with --debug-init is broken, bug#65267: 30.0.50; modifying debug-ignored-errors during startup with --debug-init is broken

[Gregory Heytings]

> > Yes.  This cannot fly, since we had end-of-file there for a long time 
> > (I see it in Emacs 20).
>
> I only wish someone would put forth an actual argument for having 
> end-of-file on debug-ignored-errors.

See NEWS.19:

** The variable 'debug-ignored-errors' specifies certain kinds of errors 
that should not enter the debugger.  Its value is a list of error 
condition symbols and/or regular expressions.  If the error has any of the 
condition symbols listed, or if any of the regular expressions matches the 
error message, then that error does not enter the debugger, regardless of 
the value of debug-on-error.

This variable is initialized to match certain common but uninteresting 
errors that happen often during editing.

To see what this means in practice, try:

emacs -Q
M-: (setq debug-ignored-errors nil) RET
M-x toggle-debug-on-error RET
"
M-x eval-buffer RET