BUG: Series[int].loc setitem with Series[int] results in Series[float]
```
>>> pd.__version__
'1.3.0.dev0+1695.g55e58542db'
>>> 
>>> s = pd.Series([0, 0])
>>> s
0    0
1    0
dtype: int64
>>> 
>>> s2 = pd.Series([42])
>>> s2
0    42
dtype: int64
>>> 
>>> s.loc[0] = s2
>>> s
0    42.0
1     0.0
dtype: float64
>>> 
```

Does not need a release note, this issue is only on master as on 1.2.4 this raises `ValueError: No axis named 1 for object type Series` which was fixed in #39358

draft, since if we merge and backport #40555 first, we can also remove the patch in this PR.
milestoned as 1.3, but if the indexing is to be changed in another PR this becomes less urgent. let's move off the milestone No what's new needed. Only changes master.

On Fri, 4 Jun 2021, 21:29 Jeff Reback, ***@***.***> wrote:

> ***@***.**** requested changes on this pull request.
>
> can you add whatsnew
>
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 LGTM @jreback OK to merge? yep