Fix wrong way of adding Error information in shutil.copytree.
diff --git a/Lib/shutil.py b/Lib/shutil.py
index dca4d2e..420802f 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -203,7 +203,7 @@
             # Copying file access times may fail on Windows
             pass
         else:
-            errors.extend((src, dst, str(why)))
+            errors.append((src, dst, str(why)))
     if errors:
         raise Error, errors