bug#22038: 25.1.50; Character folding issues with isearch

[Eli Zaretskii]

> From: Stephen Berman <stephen.berman@gmx.net>
> Date: Sat, 28 Nov 2015 17:07:22 +0100
> 
> Issue 1: Please support having multiple characters match a single
> string in searches, so that e.g. "ss" can match the German letter "ß".

You mean, allow equivalent strings be of different length, I believe.
(That's the only way I could parse "multiple characters matching a
single string".)  We will have that, but it won't allow "ss" to match
"ß", unless you customize character-fold-table to include that.  The
reason is that "ß" doesn't have any decompositions in the Unicode
database, so the default character-fold-table doesn't include any
expansions for it.