Bug #1458017: make distutils.Log._log more forgiving when passing in

msg strings with '%', but without format args.

log.py

@@ -20,7 +20,12 @@ class Log:
 
     def _log(self, level, msg, args):
         if level >= self.threshold:
-            print msg % args
+            if not args:
+                # msg may contain a '%'. If args is empty,
+                # don't even try to string-format
+                print msg
+            else:
+                print msg % args
             sys.stdout.flush()
 
     def log(self, level, msg, *args):