message: Warn if creating a MultiRNNCell with multiple identical cell objects.
  This is likely a bug.
diff: @@ -1261,6 +1261,11 @@ class MultiRNNCell(RNNCell):
  raise TypeError(
  "cells must be a list or tuple, but saw: %s." % cells)
  + if len(set([id(cell) for cell in cells])) < len(cells):
  + logging.log_first_n(logging.WARN,
  + "At least two cells provided to MultiRNNCell "
  + "are the same object and will share weights.", 1)
  +
  self._cells = cells
  for cell_number, cell in enumerate(self._cells):
  # Add Checkpointable dependencies on these cells so their variables get
  