automodapi inheritance diagram self-looping arrow

Most people probably won't encounter this but it does happen when you have a subclass that shares the same name as its parent class. Example:

```python
from astropy.modeling import models as _models

class Box1D(_models.Box1D):
"""Extends the original Box1D with some special magic."""
pass
```

The resultant inheritance diagram using `automodapi` makes a loop of the class on itself. It is harmless but appears quite funny and potentially confusing. I don't even know if a fix is possible or necessary. Just want to point it out.


Start with the Box1D reproducer in the issue and trace how automodapi builds inheritance diagrams for classes sharing a name with a parent. Confirm the generated diagram contains a self-loop, then verify that the completed change removes that arrow without breaking other inheritance diagrams.

Written by the indexing model from the issue text.