Fix pylint warning about indentation width

Author: benlangmuir

utils/round-trip-syntax-test

@@ -79,7 +79,7 @@ class RoundTripTask(object):
         stdout_contents = self.stdout.decode('utf-8', errors='replace')
 
         if contents == stdout_contents:
-          return None
+            return None
 
         lines = difflib.unified_diff(contents, stdout_contents,
                                      fromfile=self.input_filename,