Adding an end/start repeat barline to score adds an end repeat barline to parts
In a score with parts adding an end/start repeat barline (:||:) to score adds an end repeat barline (:|) to the parts, and vice versa.
Similar with changing an end repeat barline to an end/start repeat barline, it only changes where you apply it, but doesn't propagate.
If there is an end repeat barline and you add a start repeat barline to the next measure, this works and results in a an end/start repear barline in score and parts.
MuseScore 2.0.3, 2.1 3d0347f, Windows 7
Not in master, af9062701, though.