Make sure ifelse is imported before the JAX test is run

tests/sandbox/test_jax.py

@@ -424,6 +424,8 @@ def test_jax_IncSubtensor():
 
 def test_jax_ifelse():
 
+    import theano.ifelse
+
     true_vals = np.r_[1, 2, 3]
     false_vals = np.r_[-1, -2, -3]