musescore/MuseScore — pull request #246 by heuchi (2013-03-10 14:45:10+00:00)
Title: Fix #18105: keep courtesy accidentals

This fix preserves courtesy accidentals when transposing:
Note::updateAccidental() does no longer remove ACC_USER accidentals
Score::upDown() removes accidentals when a pitch change occurs to a note, this also removes ACC_USER accidentals.