A few more NOVA_BIN_DIR cleanups.

Change-Id: I1d1225c894f1857a3723e01f18d0f0dade670dc9
diff --git a/stack.sh b/stack.sh
index dbb53ec..aca4cff 100755
--- a/stack.sh
+++ b/stack.sh
@@ -1543,7 +1543,7 @@
     add_nova_opt "s3_affix_tenant=True"
 fi
 
-screen_it zeromq "cd $NOVA_DIR && $NOVA_DIR/bin/nova-rpc-zmq-receiver"
+screen_it zeromq "cd $NOVA_DIR && $NOVA_BIN_DIR/nova-rpc-zmq-receiver"
 
 # Launch the nova-api and wait for it to answer before continuing
 if is_service_enabled n-api; then