REGR: DataFrame reduction with min_count
- [ ] closes #41074
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry

tests copied from #41701; i think this gets at the root problem cc @simonjayhawkins

a regression on master right? > a regression on master right?

no 1.2.4 #41074 ok so this seems backportable. we should include the release note here. just copied over the whatsnew note from #41701 ok so plan is to merge this to master, then the backport to 1.2.5 > ok so plan is to merge this to master, then the backport to 1.2.5

I could maybe test this backportable (will be tomorrow) first to be sure. Or go ahead and merge and backport and sort out issues (if any) afterwards. > > ok so plan is to merge this to master, then the backport to 1.2.5
> 
> I could maybe test this backportable (will be tomorrow) first to be sure. Or go ahead and merge and backport and sort out issues (if any) afterwards.

#41758 - all seems good (test failures look unrelated) 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 1.2.x
$ git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
$ git cherry-pick -m1 f7dd14bd62e587b6846616844a79a159e0d7e61c
```

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

```
$ git commit -am 'Backport PR #41711: REGR: DataFrame reduction with min_count'
```

4. Push to a named branch :

```
git push YOURFORK 1.2.x:auto-backport-of-pr-41711-on-1.2.x
```

5. Create a PR against branch 1.2.x, I would have named this PR:

> "Backport PR #41711 on branch 1.2.x"

And apply the correct labels and milestones.

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

If these instruction are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                 @meeseeksdev backport 1.2.x 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 1.2.x
$ git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
$ git cherry-pick -m1 f7dd14bd62e587b6846616844a79a159e0d7e61c
```

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

```
$ git commit -am 'Backport PR #41711: REGR: DataFrame reduction with min_count'
```

4. Push to a named branch :

```
git push YOURFORK 1.2.x:auto-backport-of-pr-41711-on-1.2.x
```

5. Create a PR against branch 1.2.x, I would have named this PR:

> "Backport PR #41711 on branch 1.2.x"

And apply the correct labels and milestones.

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

If these instruction are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                