PEP8 cleanup: ensure lines are shorter than 80 characters

Caught by PEP8. This is important for Sugar because the XO has a small screen
where long lines would make the code hard to understand (because you need to
constantly scroll horizontally).

Reviewed-by: James Cameron <quozl@laptop.org>
Acked-by: Simon Schampijer<simon@schampijer.de>
CC: Aleksey Lim <alsroot@member.fsf.org>

src/sugar/activity/activity.py

@@ -569,7 +569,8 @@ class Activity(Window, gtk.Container):
         if self._closing:
             self._show_keep_failed_dialog()
             self._closing = False
-        raise RuntimeError('Error saving activity object to datastore: %s', err)
+        raise RuntimeError('Error saving activity object to datastore: %s',
+                           err)
 
     def _cleanup_jobject(self):
         if self._jobject: