Memory leak during playback

During playback the cursor lags behind and RAM usage constantly grows for each played note.

There is probably a memory leak in function Chord::layoutStem1, in particular when dealing with hooks (lines 1142-1153).
Here is the back-trace of the leaking function:
# 0 Ms::Chord::layoutStem1() [C:/Git_packages/MuseScore/libmscore/chord.cpp:1146]
# 1 Ms::Measure::layoutChords0() [C:/Git_packages/MuseScore/libmscore/measure.cpp:340]
# 2 Ms::Measure::layoutStage1() [C:/Git_packages/MuseScore/libmscore/measure.cpp:3569]
# 3 Ms::Score::doLayout() [C:/Git_packages/MuseScore/libmscore/layout.cpp:604]
# 4 Ms::Score::update() [C:/Git_packages/MuseScore/libmscore/cmd.cpp:151]
# 5 Ms::Seq::heartBeatTimeout() [C:/Git_packages/MuseScore/mscore/seq.cpp:1167]
# 6 Ms::Seq::qt_static_metacall() [C:/Git_packages/MuseScore/build.debug/mscore/moc_seq.cxx:76]

Windows 8, rev. 43b7d1d50