Octave transposing instrument doesn't change clef properly in part when toggling concertpitch

1. Create a score including "Guitar (Treble clef)"
2. Generate parts
3. Switch to the "Guitar (Treble clef)" part
4. Toggle Concert pitch once and notice the G clef becomes a G8vb clef, as expected
5. Toggle Concert pitch again

Expected result: Clef returns to G clef (just like it does in master score)

Actual result: it stays a G8vb clef

Another scenario:

1. Create a score including "Guitar (Treble clef)"
2. Toggle Concert pitch once and notice the G clef becomes a G8vb clef, as expected
3. Generate parts
4. Switch to the "Guitar (Treble clef)" part and notice the G clef, as expected
5. Toggle Concert pitch

Expected result: Clef turns into G8vb clef (just like it does in master score)

Actual result: it stays a G clef

In either case the clefs are what they should be after a save/close/open.

Doing the same thing with Tuba (treble clef) works as expected (i.e. clef changes back and forth right away, along with the keysig), here we transpose 2 octaves plus a major second.

Windows 7, MuseScore 2.1