fix #364 -- x[.ellipsis] returns self instead of a "copy"

[davidkoski]

Proposed changes

Remove special case for x[...] that just returns self. Test added.

Note: CI will fail until #366 is merged and this is rebased.

Checklist

Put an x in the boxes that apply.

• I have read the CONTRIBUTING document
• I have run pre-commit run --all-files to format my code / installed pre-commit prior to committing changes
• I have added tests that prove my fix is effective or that my feature works
• I have updated the necessary documentation (if needed)

[angeloskath]

👍