• backport of daemon: release sandbox even when NetworkDisabled #46651
• Fix Bug: docker hang on restarting when bridge set to none. #42461
• Fix Stale network sandboxes causing long docker startup time #46583
• Closes Fix: don't create sandbox when bridge is none to avoid docker restart hang. #42454. Commit message has been improved and a couple comments have been added.

- What I did

When the default bridge is disabled by setting dockerd's --bridge=none option, the daemon still creates a sandbox for containers with no network attachment specified. In that case NetworkDisabled will be set to true.

However, currently the releaseNetwork call will early return if NetworkDisabled is true. Thus, these sandboxes won't be deleted until the daemon is restarted. If a high number of such containers are created, the daemon would then take few minutes to start.

As a side note, NetworkDisabled semantics is weird/broken and should be revised:

• On one hand a sandbox is created even if NetworkDisbled is set. Thus it allows these containers to be manually connected to other networks;
• OTOH, when manually connecting such container to a network nothing happens and no error is returned (ie. no interface and no route provisioned, no embedded DNS, etc...);

- Description for the changelog

• Fix a bug that would prevent network sandboxes to be properly deleted when stopping containers with no network attachment are specified and dockerd's --bridge=none option is specified.

- A picture of a cute animal (not mandatory but encouraged)