Existing epic on nested level 7 can not be added

Summary

It's not possible to add an existing epic on nested level 7 (it works when adding new epic).

Steps to reproduce

• Navigate to an epic on nested level 6
• try to add an existing epic as a child of the epic

What is the current bug behavior?

Error This epic cannot be added. One or more epics would exceed the maximum depth (7) from its most distant ancestor. is displayed

What is the expected correct behavior?

The child epic is added