Index: Lib/lib2to3/refactor.py
===================================================================
--- Lib/lib2to3/refactor.py	(révision 68984)
+++ Lib/lib2to3/refactor.py	(copie de travail)
@@ -339,10 +339,10 @@
         if old_text == new_text:
             self.log_debug("No changes to %s", filename)
             return
-        self.print_output(diff_texts(old_text, new_text, filename))
         if write:
             self.write_file(new_text, filename, old_text)
         else:
+            self.print_output(diff_texts(old_text, new_text, filename))
             self.log_debug("Not writing changes to %s", filename)
 
     def write_file(self, new_text, filename, old_text):