fix test_step.py

Author: Stephen Hogg

pymc3/tests/test_step.py

@@ -963,15 +963,15 @@ def test_bad_init_nonparallel(self):
             HalfNormal("a", sigma=1, testval=-1, transform=None)
             with pytest.raises(SamplingError) as error:
                 sample(init=None, chains=1, random_seed=1)
-            error.match("Bad initial")
+            error.match("Initial evaluation")
 
     @pytest.mark.skipif(sys.version_info < (3, 6), reason="requires python3.6 or higher")
     def test_bad_init_parallel(self):
         with Model():
             HalfNormal("a", sigma=1, testval=-1, transform=None)
-            with pytest.raises(ParallelSamplingError) as error:
+            with pytest.raises(SamplingError) as error:
                 sample(init=None, cores=2, random_seed=1)
-            error.match("Bad initial")
+            error.match("Initial evaluation")
 
     def test_linalg(self, caplog):
         with Model():