Fix a bug in traceback.format_exception_only() that led to an error
being raised when print_exc() was called without an exception set.
In version 2.4, this printed "None", restored that behavior.
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index b3c5a50..b42dbc4 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -149,6 +149,10 @@
str_value = '<unprintable %s object>' % X.__name__
self.assertEqual(err[0], X.__name__ + ': ' + str_value + '\n')
+ def test_without_exception(self):
+ err = traceback.format_exception_only(None, None)
+ self.assertEqual(err, ['None\n'])
+
def test_main():
run_unittest(TracebackCases)
diff --git a/Lib/traceback.py b/Lib/traceback.py
index 75e1fcf..31b8255 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -170,7 +170,7 @@
# would throw another exception and mask the original problem.
if (isinstance(etype, BaseException) or
isinstance(etype, types.InstanceType) or
- type(etype) is str):
+ etype is None or type(etype) is str):
return [_format_final_exc_line(etype, value)]
stype = etype.__name__
diff --git a/Misc/NEWS b/Misc/NEWS
index ae14e8f..c1a3a6c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -56,6 +56,10 @@
Library
-------
+- Fix a bug in traceback.format_exception_only() that led to an error
+ being raised when print_exc() was called without an exception set.
+ In version 2.4, this printed "None", restored that behavior.
+
- Make webbrowser.BackgroundBrowser usable in Windows (it wasn't because
the close_fds arg to subprocess.Popen is not supported).