>> Subject: [PATCH 2/2] Extract common code for adding text properties
>
>> +      (let ((new-value (if append
>> +                           (append (if (listp prev) prev (list prev)) val)
>> +                         (append val (if (listp prev) prev (list prev))))))
>
> I would suggest to factor out the (if (listp prev) prev (list prev))
> from these expressions.

And done.