cli: allManagementSubCommands: improve handling of plugin stubs

The allManagementSubCommands function is used to present plugin-commands
in the docker --help output; these commands are included in the "management
commands" section, but for plugins we don't know if they have sub-commands.

However, plugin stubs may be hidden (for placeholders that are not yet loaded),
or not be runnable, which was previously ignored.

This patch treats plugin-stubs the same as other commands, with the exception
of checking if they have subcommands (which is not yet known for plugin-stubs).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 259df25a96)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/cobra.go

@@ -376,13 +376,10 @@ func orchestratorSubCommands(cmd *cobra.Command) []*cobra.Command {
 func allManagementSubCommands(cmd *cobra.Command) []*cobra.Command {
 	cmds := []*cobra.Command{}
 	for _, sub := range cmd.Commands() {
-		if isPlugin(sub) {
-			if invalidPluginReason(sub) == "" {
-				cmds = append(cmds, sub)
-			}
+		if invalidPluginReason(sub) != "" {
 			continue
 		}
-		if sub.IsAvailableCommand() && sub.HasSubCommands() {
+		if sub.IsAvailableCommand() && (isPlugin(sub) || sub.HasSubCommands()) {
 			cmds = append(cmds, sub)
 		}
 	}