Make gdbm and dumbdbm use byte strings.  Updated their tests.
diff --git a/Lib/test/test_anydbm.py b/Lib/test/test_anydbm.py
index f980354..f5eae42 100644
--- a/Lib/test/test_anydbm.py
+++ b/Lib/test/test_anydbm.py
@@ -21,13 +21,13 @@
             pass
 
 class AnyDBMTestCase(unittest.TestCase):
-    _dict = {'0': '',
-             'a': 'Python:',
-             'b': 'Programming',
-             'c': 'the',
-             'd': 'way',
-             'f': 'Guido',
-             'g': 'intended'
+    _dict = {'0': b'',
+             'a': b'Python:',
+             'b': b'Programming',
+             'c': b'the',
+             'd': b'way',
+             'f': b'Guido',
+             'g': b'intended',
              }
 
     def __init__(self, *args):
@@ -44,7 +44,7 @@
     def test_anydbm_modification(self):
         self.init_db()
         f = anydbm.open(_fname, 'c')
-        self._dict['g'] = f['g'] = "indented"
+        self._dict['g'] = f['g'] = b"indented"
         self.read_helper(f)
         f.close()