`rgrep' not working

[Massimo Gengarelli]

Dears,

I'm actually using `GNU Emacs 25.0.50.1 (x86_64-apple-darwin14.0.0, NS
appkit-1343.16 Version 10.10.1 (Build 14B23)) of 2014-11-23 on
napi.home' on Mac OS X (Yosemite) and I am having a little issue with
the `rgrep' command which is not working.

Everytime I try to run it, I receive a weird error like:
`Symbol's function definition is void: \,'

Please note that `grep-find', `lgrep' and `ag' are all working properly.
I am not using any weird plugin for grep, and the issue is reproducible
even without loading my init.el file (i.e., running emacs -Q).

Since I'm quite a newbie with Emacs, could you please help me in
debugging?  I thought that rgrep was an user-friendly version of
`grep-find', but I think I was wrong since the latter is working. :-)

I also tried the following:

> C-h f rgrep
> With C-u prefix, you can edit the constructed shell command line
> before it is executed.
> With two C-u prefixes, directly edit and run `grep-find-command'.

But apparently the issue is at an higher level as I am not able to edit
the constructed shell command line.  The two C-u prefixes are working
fine though.

Is there something I am missing?

Thanks and regards,
--
Massimo Gengarelli
M: +33 (0)6 43 87 57 67
E: massimo.gengarelli@gmail.com