sh-mode highlight issue

[Wayne Cuddy]

I'm not sure if this has been reported before, please forgive me if
this is repetitious.

I'm running 9.8t and have not had a chance to upgrade to the
latest/greatest yet but I don't see mention of this issue being
corrected in the changelog. The closest I could find was comments from
9.7y:

    + improve vile-sh-filt for these cases:
    + "${number}"
    + "$(commands)"
    + "$((expression))"
    + "${name#value}", etc.


The issue concerns $((expression)) expansions in variable assignments,
but may not be limited to just this case.

var="prefix$((5*5))suffix"

prefix appears correctly highlighted, suffix does not, it seems the
syntax highlighting terminates after the final ')' character.

Wayne