Remove import of unittest_tools in basic.py. tensor.verify_grad now needs to be passed a valid rng.

theano/tensor/basic.py

@@ -3577,9 +3577,8 @@ def verify_grad(op, pt, n_tests=2, rng=None, eps=None, tol=None, mode=None, cast
         tol = __builtin__.max(_type_tol[str(p.dtype)] for p in pt)
 
     if rng is None:
-        rng = numpy.random
-        from theano import tests as theano_tests # TODO This is an ugly import. Fix?
-        theano_tests.unittest_tools.seed_rng()
+        raise TypeError('rng should be a valid instance of numpy.random.RandomState.',
+                'You may want to use theano.tests.unittest_tools.verify_grad instead of theano.tensor.verify_grad.')
 
     def function(inputs, output):
         if mode is None: