sugar.util: use logging.exception instead of traceback.format_exc()

logging.exception() handles exceptions nicely for us, no need to explicitly
use traceback.

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

src/sugar/util.py

@@ -29,7 +29,6 @@ import gettext
 import tempfile
 import logging
 import atexit
-import traceback
 
 
 _ = lambda msg: gettext.dgettext('sugar-toolkit', msg)
@@ -336,7 +335,7 @@ def _cleanup_temp_files():
         try:
             os.unlink(path)
         except:
-            logging.error(traceback.format_exc())
+            logging.exception('Exception occured in _cleanup_temp_files')
 
 atexit.register(_cleanup_temp_files)