Input cursor jumps to beginning of measure while entering beamed notes onto percussion staff

Ubuntu Studio 14.04, GIT commit: e176e25

1) new score, triangle or other unpitched percussion instrument
2) first measure, note entry
3) "4" to select eighth note duration
4) double click a drum palette note repeatedly

Result: note input cursor jumps to beginning of measure on every other note

Similar but slightly different when using sixteenths - sometimes the cursor jumps all the way to before the barline, other times to just after the barline.