vendor: update docker/cli (ab688a9a79a1) and docker/docker (3998dffb806f)

Signed-off-by: Tibor Vass <tibor@docker.com>

vendor/github.com/docker/cli/cli-plugins/manager/manager.go

@@ -1,6 +1,7 @@
 package manager
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -27,10 +28,23 @@ func (e errPluginNotFound) Error() string {
 	return "Error: No such CLI plugin: " + string(e)
 }
 
+type errPluginRequireExperimental string
+
+// Note: errPluginRequireExperimental implements notFound so that the plugin
+// is skipped when listing the plugins.
+func (e errPluginRequireExperimental) NotFound() {}
+
+func (e errPluginRequireExperimental) Error() string {
+	return fmt.Sprintf("plugin candidate %q: requires experimental CLI", string(e))
+}
+
 type notFound interface{ NotFound() }
 
 // IsNotFound is true if the given error is due to a plugin not being found.
 func IsNotFound(err error) bool {
+	if e, ok := err.(*pluginError); ok {
+		err = e.Cause()
+	}
 	_, ok := err.(notFound)
 	return ok
 }
@@ -117,12 +131,14 @@ func ListPlugins(dockerCli command.Cli, rootcmd *cobra.Command) ([]Plugin, error
 			continue
 		}
 		c := &candidate{paths[0]}
-		p, err := newPlugin(c, rootcmd)
+		p, err := newPlugin(c, rootcmd, dockerCli.ClientInfo().HasExperimental)
 		if err != nil {
 			return nil, err
 		}
-		p.ShadowedPaths = paths[1:]
-		plugins = append(plugins, p)
+		if !IsNotFound(p.Err) {
+			p.ShadowedPaths = paths[1:]
+			plugins = append(plugins, p)
+		}
 	}
 
 	return plugins, nil
@@ -159,12 +175,19 @@ func PluginRunCommand(dockerCli command.Cli, name string, rootcmd *cobra.Command
 		}
 
 		c := &candidate{path: path}
-		plugin, err := newPlugin(c, rootcmd)
+		plugin, err := newPlugin(c, rootcmd, dockerCli.ClientInfo().HasExperimental)
 		if err != nil {
 			return nil, err
 		}
 		if plugin.Err != nil {
 			// TODO: why are we not returning plugin.Err?
+
+			err := plugin.Err.(*pluginError).Cause()
+			// if an experimental plugin was invoked directly while experimental mode is off
+			// provide a more useful error message than "not found".
+			if err, ok := err.(errPluginRequireExperimental); ok {
+				return nil, err
+			}
 			return nil, errPluginNotFound(name)
 		}
 		cmd := exec.Command(plugin.Path, args...)