Since nobody reacted in the last 3 days, I guess that means there is nothing to change, so I'm sending the patch here.

Jean-Christophe 

Begin forwarded message:

From: Jean-Christophe Helary <jean.christophe.helary@gmail.com>
Subject: Re: Trimming strings, /emacs/lisp/emacs-lisp/subr-x.el modification
Date: May 10, 2017 23:26:04 GMT+9
To: Emacs developers <emacs-devel@gnu.org>

Hopefully last fixes.

I've added the \\(?: ... \\) parens to make sure we capture any potential issue with \|.

Is there anything else I've missed ?

Jean-Christophe


===========================
Add optional regexps for subr-x.el trimming functions

* lisp/emacs-lisp/subr-x.el (string-trim-left, string-trim-right, string-trim): add optional regexps that default on the original behavior.
===========================