--- a/tests/test-commandserver.py	Mon Mar 03 15:50:48 2014 +0900
+++ b/tests/test-commandserver.py	Mon Mar 03 15:50:51 2014 +0900
@@ -104,6 +104,9 @@
     # make sure --config doesn't stick
     runcommand(server, ['id'])
 
+    # negative return code should be masked
+    runcommand(server, ['id', '-runknown'])
+
 def inputeof(server):
     readchannel(server)
     server.stdin.write('runcommand\n')