message: [migration] bug fix in dashboard migration (bebcf3fed1fe_)
  fix a bug in handle empty rows
diff: @@ -351,13 +351,13 @@ def convert(positions, level, parent, root):
  # they can be a list of charts, or arranged in columns, or mixed
  for layer in layers:
  if len(layer) == 0:
  - return
  + continue
  if len(layer) == 1 and parent['type'] == COLUMN_TYPE:
  chart_holder = get_chart_holder(layer[0])
  root[chart_holder['id']] = chart_holder
  parent['children'].append(chart_holder['id'])
  - return
  + continue
  # create a new row
  row_container = get_row_container()
  