bug#20074: edebug tracing can't be stopped with 'S'

[Eli Zaretskii <eliz@gnu.org>]

> Date: Tue, 10 Mar 2015 14:42:07 -0600
> From: Mario Valencia <mariovalspi@gmail.com>
> 
> I start emacs with "runemacs -Q", on windows 8.
> Then i write the following function in the scratch buffer:
> 
> (defun forever ()
> (interactive)
> (while t (message "doing nothing")))
> 
> I then press C-u C-M-x to instrument the function for debugging. Then i
> do M-x forever. Then i press 't' to start tracing, and edebug starts
> tracing the code correctly. However, if i press 'S' to stop, it doesn't
> work. Pressing many 'S' commands repeatedly apparently only cause edebug
> to evaluate the 'while' expression faster. Pressing 'q', <SPC>, 'n', do
> not seem to stop edebug either, they only appear to speed up the
> evaluation of the code. I have to press C-g then 'q' to return me to the
> toplevel.

First, I see this on GNU/Linux as well, so it's not Windows-specific,
at least.

And second, did this ever work as you expect?  I tried as far back as
Emacs 23.3, and I see the same behavior.  Moreover, the ELisp manual
doesn't say anything about 'S' interrupting a trace, at least
according to my reading.