bug#37521: breakage in emacs 26.3 + nxml

[Allin Cottrell <cottrell@wfu.edu>]

There's a broken interaction between unescaped '>' (ASCII 62) and
apostrophe (ASCII 39) when editing an XML file in nxml mode in emacs
26.3. (Version 26.2 was OK.)

At the first apostrophe following an unescaped '>', the font color
switches to "within delimiters" mode, and, depending on the context,
certain nxml editing commands stop working properly.

Here are two little examples. The first just shows the unwanted change
in face:

<?xml version="1.0"?>

<p>Here's some text, including the inequality 3 > 2. And here's
what happens in following text once an apostrophe comes along.
</p>

The second example shows what happens when the apostrophe is inside a
tag. If you delete the trailing "</p>" below, then try to insert it
again via the shortcut C-c C-f, it's "</tt>" that gets inserted
instead:

<?xml version="1.0"?>

<p>Here's some text, including the inequality 3 > 2. And here is an
apostrophe inside a tag: <tt>'</tt>. Plus some following text and
so on.</p>

-- 
Allin Cottrell
Department of Economics
Wake Forest University, NC