TST: Add test for loc not updating cache correctly
- [x] closes #47867 (Replace xxxx with the Github issue number)
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.


All the setitem and getitem steps are necessary to produce the bug. Reduced it as far as possible
> All the setitem and getitem steps are necessary to produce the bug. Reduced it as far as possible

you did explicitly check that this exact test fails on 1.4.3? if so merge when ready. lgtm. Thanks @phofl  > All the setitem and getitem steps are necessary to produce the bug. Reduced it as far as possible

maybe worth adding a code comment to not alter the test as all steps are necessary to avoid clean-ups or refactors changing it. Yes, used 1.4.3 to narrow it down to this test > Yes, used 1.4.3 to narrow it down to this test

sure. the "Reduced it as far as possible" created some doubt. so was just checking. Good point, added a comment Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

```
git checkout 1.4.x
git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
git cherry-pick -x -m1 4485f15597a1be751fc0c4aeccd11012f22782e6
```

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

```
git commit -am 'Backport PR #47949: TST: Add test for loc not updating cache correctly'
```

4. Push to a named branch:

```
git push YOURFORK 1.4.x:auto-backport-of-pr-47949-on-1.4.x
```

5. Create a PR against branch 1.4.x, I would have named this PR:

> "Backport PR #47949 on branch 1.4.x (TST: Add test for loc not updating cache correctly)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the `Still Needs Manual Backport` label once the PR gets merged.

If these instructions are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                 https://github.com/pandas-dev/pandas/pull/47954