Index: Lib/logging/__init__.py
===================================================================
--- Lib/logging/__init__.py	(revision 71354)
+++ Lib/logging/__init__.py	(working copy)
@@ -764,11 +764,11 @@
                 stream.write(fs % msg)
             else:
                 try:
-                    if (isinstance(msg, unicode) or
-                        getattr(stream, 'encoding', None) is None):
+                    if (isinstance(msg, unicode) and
+                        getattr(stream, 'encoding', None)):
+                        stream.write(fs.decode(stream.encoding) % msg)
+                    else:
                         stream.write(fs % msg)
-                    else:
-                        stream.write(fs % msg.encode(stream.encoding))
                 except UnicodeError:
                     stream.write(fs % msg.encode("UTF-8"))
             self.flush()
Index: Lib/test/test_logging.py
===================================================================
--- Lib/test/test_logging.py	(revision 71354)
+++ Lib/test/test_logging.py	(working copy)
@@ -894,6 +894,7 @@
         message = u'\u0434\u043e \u0441\u0432\u0438\u0434\u0430\u043d\u0438\u044f'
         #Ensure it's written in a Cyrillic encoding
         writer_class = codecs.getwriter('cp1251')
+        writer_class.encoding = 'cp1251'
         stream = cStringIO.StringIO()
         writer = writer_class(stream, 'strict')
         handler = logging.StreamHandler(writer)