add do_constant_folding->False onto MPIRecv

theano/tensor/io.py

@@ -133,6 +133,9 @@ class MPIRecv(Op):
     def infer_shape(self, node, shapes):
         return [None, self.shape]
 
+    def do_constant_folding(self, node):
+        return False
+
 class MPIRecvWait(Op):
     """
     An operation to wait on a previously received array using MPI

theano/tensor/tests/test_mpi.py

@@ -16,3 +16,8 @@ def test_send():
     sendnode = y.owner.inputs[0].owner
     assert sendnode.op.dest == 1
     assert sendnode.op.tag  == 11
+
+def test_can_make_function():
+    x = recv((5,5), 'float32', 0, 11)
+    y = x+1
+    assert theano.function([], [y])