message: Add index fix again
  This was changed on /develop to fix an issue where the incorrect
  index was being used in a condition to handle literal edge cases
  of dragging room tiles to start or end of an ordered sublist.
diff: @@ -56,10 +56,13 @@ RoomListActions.tagRoom = function(matrixClient, room, oldTag, newTag, oldIndex,
  newTag === oldTag && oldIndex < newIndex
  ) ? 1 : 0;
  - const prevOrder = newIndex === 0 ?
  - 0 : newList[offset + newIndex - 1].tags[newTag].order;
  - const nextOrder = newIndex === newList.length ?
  - 1 : newList[offset + newIndex].tags[newTag].order;
  + const indexBefore = offset + newIndex - 1;
  + const indexAfter = offset + newIndex;
  +
  + const prevOrder = indexBefore <= 0 ?
  + 0 : newList[indexBefore].tags[newTag].order;
  + const nextOrder = indexAfter >= newList.length ?
  + 1 : newList[indexAfter].tags[newTag].order;
  metaData = {
  order: (prevOrder + nextOrder) / 2.0,
  