Change instrument changes transposition incorrectly (0.9.6)

Steps to reproduce bug
1. Open attached file: "transpositions of more than an octave.mscz"
2. Right-click on an empty part of the Baritone staff and choose "Staff Properties..."
3. Click "Change Instrument..." and choose tenor saxophone
4. Press "OK" to dismiss Staff Properties dialog
5. Deselect "Concert Pitch" to show the transposing score

Expected behavior: Notes and key signature for the first and second staves should be identical. Staff Properties dialog should show a transposition of "Major Second + octave 1".

Actual behavior: Notes and key signature for the second staff is incorrect. Staff Properties dialog actually shows a transposition of "Perfect unison + octave 1" for the second staff.

MuseScore version: r. 2960 nightly

(Operating System: Windows 7)

first reported by Peter B: http://musescore.org/node/5031#comment-14677