Make gdbm and dumbdbm use byte strings.  Updated their tests.
diff --git a/Lib/test/test_whichdb.py b/Lib/test/test_whichdb.py
index f2652c1..6cb5e4f 100644
--- a/Lib/test/test_whichdb.py
+++ b/Lib/test/test_whichdb.py
@@ -51,7 +51,7 @@
         self.assertEqual(name, whichdb.whichdb(_fname))
         # Now add a key
         f = mod.open(_fname, 'w')
-        f["1"] = "1"
+        f["1"] = b"1"
         f.close()
         self.assertEqual(name, whichdb.whichdb(_fname))
     setattr(WhichDBTestCase,"test_whichdb_%s" % name, test_whichdb_name)