Editing a term updates all terms with the same name or slug, regardless of what taxonomy it is in.

[desrosj]

Steps to reproduce.

1. Fresh WordPress install.
2. Add a post category.
3. Add a post tag with the same title.
4. Edit the post category title.
5. Notice the post tag title also changed.

This also happens when editing the post slug. Does not matter if taxonomies are hierarchical/non-hierarchical. Also renames terms in custom taxonomies. Editing a term's parent does not change other term parents. Only specific to name and slug.

[helen]

Duplicate of #5809.