--- a/tests/test-rebase-parameters.t	Sat Nov 16 15:46:29 2013 -0500
+++ b/tests/test-rebase-parameters.t	Sun Nov 17 18:21:58 2013 -0500
@@ -83,6 +83,10 @@
   abort: empty "rev" revision set - nothing to rebase
   [255]
 
+  $ hg rebase --source '1 & !1'
+  abort: empty "source" revision set - nothing to rebase
+  [255]
+
   $ hg rebase
   nothing to rebase
   [1]