Crash on undo of staff bracket deletion

1. Open Drums.mid
2. In MIDI import panel set checkbox to split drum track and click Apply
3. Select staff bracket and press Del
4. Press Ctrl+Z to undo the deletion
5. Crash

Related:
1. Open Promenade
2. Select staff bracket and press Del
3. Press Ctrl+Z to undo the deletion
4. No actual undo - bracket doesn't appear

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Using MuseScore 2.0, this commit. OS - Kubuntu 12.10.
Latest Mac version was 2013-08-12-1205-64ba787.