Strings portamento gliss. always ends with 1st note repeated, pizzicato

When writing for strings (solo or section), a portamento glissando between two notes always causes the first note to be repeated, pizzicato, when the second note is reached. The attached file demonstrates. It uses the MuseScore_General.sf3 soundbank, but has also been tested with the .sf2 soundbank and the MuseScore-tweaked Aegean Symphony Orchestra soundbank.