bug#12957: 24.2.50; unable to get elisp backtrace with (setq debug-on-error t)

[Stefan Monnier]

> I am seeing this for some time. using emacs-24 branch head.  When I do
> `M-x toggle-debug-on-error', I get the backtrace for elisp errors but
> for the first time only.  The second time onwards emacs unable to emit
> the backtrace.

While the first backtrace is displayed, debug-on-error is temporarily
reset to nil.  So the behavior you describe could be explained if you
don't `q' or `c' from the first backtrace.


        Stefan