Fix orthogonal indexing with a scalar

[dcherian]

Fixes #1931

TODO:

• [x] Add unit tests and/or doctests in docstrings
• [x] Add docstrings and API docs for any new/modified user-facing classes and functions
• [x] Changes documented in docs/release.rst
• [ ] GitHub Actions have all passed
• [ ] Test coverage is 100% (Codecov passes)

[jhamman]

Thanks @dcherian -- looks good to me. No idea why Appveyor isn't running though.

@zarr-developers/steering-council -- I don't have access to our appveyor account. Seems like another reason to address https://github.com/zarr-developers/zarr-python/issues/1905

[dcherian]

OK I'll try and add a hypothesis test for this later.

[dcherian]

@jhamman I have reproduced the failure with a hypothesis test now (#1746 ).

This branch makes that test always pass (it seems like)

Should I point that PR at main or V3?

[jhamman]

@dcherian - My preference is that we get #1746 into the v3 branch or both.

[joshmoore]

No idea why Appveyor isn't running though.

"AppVeyor was unable to build non-mergeable pull request" -- perhaps it was the change of the default branch?

@zarr-developers/steering-council -- I don't have access to our appveyor account. Seems like another reason to address #1905

Not sure how I log in either at this point?! (Things look to have changed)

I'd propose we get this and any other regressions out as 2.18.3 (ignoring the job failure).

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 99.98%. Comparing base (c72d0e2) to head (1b09c5e). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1947 +/- ## ======================================= Coverage 99.98% 99.98% ======================================= Files 38 38 Lines 14703 14714 +11 ======================================= + Hits 14701 14712 +11 Misses 2 2 ``` | [Files](https://app.codecov.io/gh/zarr-developers/zarr-python/pull/1947?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zarr-developers) | Coverage Δ | | |---|---|---| | [zarr/core.py](https://app.codecov.io/gh/zarr-developers/zarr-python/pull/1947?src=pr&el=tree&filepath=zarr%2Fcore.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zarr-developers#diff-emFyci9jb3JlLnB5) | `100.00% <100.00%> (ø)` | | | [zarr/tests/test\_core.py](https://app.codecov.io/gh/zarr-developers/zarr-python/pull/1947?src=pr&el=tree&filepath=zarr%2Ftests%2Ftest_core.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zarr-developers#diff-emFyci90ZXN0cy90ZXN0X2NvcmUucHk=) | `99.94% <100.00%> (+<0.01%)` | :arrow_up: |