musescore/MuseScore — pull request #1583 by MarcSabatella (2014-12-28 01:43:41+00:00)
Title: fix #42541: drum grace notes laid out incorrectly on load

See detailed comments in issue thread. The following fixes the issue and shouldn't cause worse problems. But I still have questions whether we need to explicitly set line of drum grace notes here and why we are doing so for drum regular notes.