Index: logging/__init__.py
===================================================================
--- logging/__init__.py	(revision 66204)
+++ logging/__init__.py	(working copy)
@@ -757,7 +757,7 @@
                 self.stream.write(fs % msg)
             else:
                 try:
-                    if hasattr(self.stream, 'encoding'):
+                    if getattr(self.stream, 'encoding', None) is not None:
                         self.stream.write(fs % msg.encode(self.stream.encoding))
                     else:
                         self.stream.write(fs % msg)
Index: test/test_logging.py
===================================================================
--- test/test_logging.py	(revision 66204)
+++ test/test_logging.py	(working copy)
@@ -860,6 +860,33 @@
         ])
 
 
+class EncodingTest(BaseTest):
+    def test_encoding_plain_file(self):
+        # In Python 2.x, a plain file object is treated as having no encoding.
+        log = logging.getLogger("test")
+        fn = tempfile.mktemp(".log")
+        # the non-ascii data we write to the log.
+        data = "foo\x80"
+        try:
+            handler = logging.FileHandler(fn)
+            log.addHandler(handler)
+            try:
+                # write non-ascii data to the log.
+                log.warning(data)
+            finally:
+                log.removeHandler(handler)
+                handler.close()
+            # check we wrote exactly those bytes, ignoring trailing \n etc
+            f = open(fn)
+            try:
+                self.failUnlessEqual(f.read().rstrip(), data)
+            finally:
+                f.close()
+        finally:
+            if os.path.isfile(fn):
+                os.remove(fn)
+
+
 # Set the locale to the platform-dependent default.  I have no idea
 # why the test does this, but in any case we save the current locale
 # first and restore it at the end.
@@ -867,7 +894,8 @@
 def test_main():
     run_unittest(BuiltinLevelsTest, BasicFilterTest,
                     CustomLevelsAndFiltersTest, MemoryHandlerTest,
-                    ConfigFileTest, SocketHandlerTest, MemoryTest)
+                    ConfigFileTest, SocketHandlerTest, MemoryTest,
+                    EncodingTest)
 
 if __name__ == "__main__":
     test_main()