The OpenStack Swift systemd services do not support a graceful reload. A plain restart will disconnect any clients (eg between proxy and user); a graceful reload should wait until requests are finished. This is supported upstream using the command "swift-init reload proxy", for example.
We currently can't support this with OSP12 and later b/c we're running Swift within containers, so postponing this for now.
Cannot be supported in containerized Swift, closing as won'tfix. Sean