Stop painting over broadcastable differences (since this could lead to a bug).

theano/scan_module/scan_utils.py

@@ -402,11 +402,6 @@ def expand(tensor_var, size):
     empty = tensor.zeros(zeros_shape,
                          dtype=tensor_var.dtype)
 
-    # Make sure to reuse the broadcast pattern of the original tensor for
-    # every dimension but the first one.
-    broadcastable = (False,) + tensor_var.broadcastable[1:]
-    empty = tensor.patternbroadcast(empty, broadcastable)
-
     return tensor.set_subtensor(empty[:shapes[0]], tensor_var)