bug#23179: 25.0.92; Restore `M-,' to continue etags search

[Eli Zaretskii]

> Cc: 23179@debbugs.gnu.org, andlind@gmail.com
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Sun, 3 Apr 2016 20:21:13 +0300
> 
> On 04/03/2016 06:32 PM, Eli Zaretskii wrote:
> 
> > Etags isn't special, I just remembered that you said at some point you
> > couldn't see how other back-ends will be able to implement a similar
> > functionality.  But if I misremembered, or if you now see a way to do
> > this with other back-ends, by all means let's do that.
> 
> Not sure what I said previously, but first and foremost, we don't have a 
> backend-agnostic spec for that similar functionality.

That's probably what you said.

> When we have it, I'm sure other backends can implement regexp-search to 
> the best of their ability.

Searching is not the problem, indeed.