Set AttachOptions.CommandName from kubectl run using corba CommandPath

This sets AttachOptions.CommandName dynamically depending on the corba Command
hierarchy. If the root command is named e.g. "oc" (for the OpenShift cli) this
will result in "oc attach" instead of the static "kubectl attach" before this
patch.

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1341450

pkg/kubectl/cmd/attach.go

@@ -53,8 +53,6 @@ func NewCmdAttach(f *cmdutil.Factory, cmdIn io.Reader, cmdOut, cmdErr io.Writer)
 		Out: cmdOut,
 		Err: cmdErr,
 
-		CommandName: "kubectl attach",
-
 		Attach: &DefaultRemoteAttach{},
 	}
 	cmd := &cobra.Command{
@@ -142,6 +140,10 @@ func (p *AttachOptions) Complete(f *cmdutil.Factory, cmd *cobra.Command, argsIn
 	}
 	p.Client = client
 
+	if p.CommandName == "" {
+		p.CommandName = cmd.CommandPath()
+	}
+
 	return nil
 }