Custom Taxonomy terms tree view not displayed correctly in backend

[jdenkers]

When adding a Custom Taxonomy to a Post Type, there is a problem with the tree view of terms in WordPress' backend which is shown when editing a post.

When a term is selected, it always moves to the top of the list.

When the selected term is a child, after saving the term is moved to the top of the list and is shown as top level term. The others childs and the parent term stay on the same place in the term list.

When the selected term is a top level term, it is also moved to the top of the list and the child terms stay on the same place in the list. Because their parent is gone, they are all shown as top level terms.

[helenyhou]

Duplicate: #10982, and many others. Behavior now alterable using a filter; see #20054.