MAINT: minor PEP8, test docstring cleanup for previous test_hierarchy commit.

Author: Ralf Gommers

scipy/cluster/tests/test_hierarchy.py

@@ -814,12 +814,13 @@ def test_leaves_list_iris_average(self):
         self.assertTrue((node.pre_order() == leaves_list(Z)).all())
 
     def test_iris_subtree_pre_order(self):
-        "Tests that pre_order() works when called on sub-trees."
+        # Tests that pre_order() works when called on sub-trees.
         X = eo['iris']
         Y = pdist(X)
         Z = linkage(X, 'single')
         node = to_tree(Z)
-        self.assertTrue(node.pre_order() == (node.get_left().pre_order() + node.get_right().pre_order()))
+        self.assertTrue(node.pre_order() == (node.get_left().pre_order()
+                                             + node.get_right().pre_order()))
 
 
 class TestCorrespond(TestCase):