Moving Stories between projects allows the creation of Epic child of another Epic

Issue Summary

It is possible to end up with an epic issue which is a child of another epic issue. If you start with a story (which is a child of an epic) and move this issue to a different project, you have the option to change the issue type. If you select epic, the issue in the new project retains its child-association to the original epic.

Steps to Reproduce

1. Create a story issue and add it to an existing epic
2. Move the story issue to another project and change the issue type to epic
3. Notice in the original epic issue that the new epic shows up as a child issue still

Expected Results

Epics should not be allowed to be children of other epics

Actual Results

Epic becomes child of another epic

Workaround

While moving the story to a different project, don't change the issue type to Epic. Once the movement to project is complete, change the issue type from the issue view. This will remove the issue's association with the parent epic of its previous project.