bug#51899: Odd highlighting in compilation mode

["積丹尼 Dan Jacobson" <jidanni@jidanni.org>]

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Save and open the attached file with emacs -Q.
You will see:
One $m is highlighted, the others and $i etc. aren't.
"/tmp/$(basename" is highlighted.


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-*- mode: compilation; default-directory: "~/" -*-
Compilation started at Wed Nov 17 01:06:26

make -n
mountpoint -q /cf/
set -xe; m=/cf/versions-$(hostname);\
if test $m -nt /var/lib/dpkg/status && test \
$m -nt /var/lib/aptitude/pkgstates; then exit; fi;\
apt-show-versions | grep -v 'not installed$' > /tmp/VERsions;\
test -s /tmp/VERsions;\
sort -o $m /tmp/VERsions || { echo try again as root first; false;}
: ${k?}
for i in /cf/versions-jidanni[]; do sed 's/:.*//' $i | sort -o /tmp/$(basename $i); done;\
comm -3 /tmp/versions-jidanni[]

Compilation finished at Wed Nov 17 01:06:26

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I have no opinions on what should be highlighted. Just be consistent.
emacs-version "27.1"