Traceback (most recent call last):
  File "/usr/lib/pitivi/python/pitivi/ui/timelineobjects.py", line 755, in _startTrimButtonClickedCb
    self._updateStartDuration()
  File "/usr/lib/pitivi/python/pitivi/ui/timelineobjects.py", line 795, in _updateStartDuration
    self._adjustControls()
  File "/usr/lib/pitivi/python/pitivi/ui/timelineobjects.py", line 808, in _adjustControls
    assert end <= self._source.factory.length
AssertionError