PixelArray `__getitem__` with single ellipsis index gives self-reference instead of new object

[aatle]

Indexing a PixelArray with [:, :], [()], and [...] should all be the same. However, only [:, :] returns a new object, which is the intuitive and expected behavior.

Note that PixelArray slicing returns another view, with data shared by both the original and the view (the surface), so the issue is not about copying.

The one case where I found that a full view and the original array differ is that each separate object can be individually closed (once) (without affecting other views).

This is a very minor issue.