--- rlcompleter.py	2010-02-10 15:16:08.695389108 +0800
+++ rlcompleter.py.1	2010-02-10 15:34:54.228322643 +0800
@@ -83,7 +83,9 @@
             self.namespace = __main__.__dict__
 
         if state == 0:
-            if "." in text:
+            if text.strip() == '':
+                self.matches = ['\t']
+            elif "." in text:
                 self.matches = self.attr_matches(text)
             else:
                 self.matches = self.global_matches(text)