map_variables: test replacement of inputs inside scan

theano/gof/tests/test_graph.py

@@ -220,6 +220,27 @@ class TestMapVariables(X):
                                  [[ 1,  3,  6],
                                   [-1, -3, -6]])
 
+    def test_leaf_inside_scan(self):
+        import numpy
+        from theano import function, scan
+
+        x = tensor.vector('x')
+        y = tensor.scalar('y')
+        z = tensor.scalar('z')
+
+        y.tag.replacement = z
+
+        s, _ = scan(lambda x: x * y, sequences=x)
+        s2, = map_variables(
+            lambda x: getattr(x.tag, "replacement", x),
+            [s])
+
+        f = function([x, y, z], [s, s2])
+        assert numpy.array_equal(
+            f(x=numpy.array([1, 2, 3]), y=1, z=2),
+            [[ 1, 2, 3],
+             [ 2, 4, 6]])
+
 
 ############
 # toposort #