Add mboxes

tests/fakes/source/close_after_connect.rb

@@ -20,7 +20,11 @@ rescue Timeout::Error
   exit 1
 end
 
-Timeout.timeout( 2 ) do
+Timeout.timeout( 3 ) do
+  # Sleep to be sure we don't try to connect too soon. That wouldn't
+  # be a problem for the destination, but it would prevent us from
+  # determining success or failure here.
+  sleep 0.5
   sock = TCPSocket.open( addr, port.to_i )
   sock.close
 end