The copying subtree shows failure message which can easily confuse users.

If copying a subtree whose nodes need to be approved in workflow, the result will be

Copy subtree Notification
Warnings:

Cannot publish object (ID = 159).
Number of nodes of source subtree - 2
Number of copied nodes - 1
Number of copied contentobjects - 2
Successfully DONE.

Before supporting a new feature for user to deal with the case of copying subtree with approval workflow, the error message needs to be clear.

And we need to document this case in our documentation.