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 


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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.
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