Revert whitespace change to comment

Author: JanEricNitschke

Lib/test/test_csv.py

@@ -959,7 +959,7 @@ def test_read_dict_no_fieldnames(self):
             self.assertEqual(reader.fieldnames, ["f1", "f2", "f3"])
 
     # Two test cases to make sure existing ways of implicitly setting
-    # fieldnames continue to work. Both arise from discussion in issue3436.
+    # fieldnames continue to work.  Both arise from discussion in issue3436.
     def test_read_dict_fieldnames_from_file(self):
         with TemporaryFile("w+", encoding="utf-8") as fileobj:
             fileobj.write("f1,f2,f3\r\n1,2,abc\r\n")