CoW: Remove todos that aren't necessary
xref https://github.com/pandas-dev/pandas/issues/56019

This should warn, row is a Series and the setitem is inplace then

The Index case is a bug at the moment, creating the df is zero copy, updating the df afterwards will propagate to the index, but will be fixed with CoW

``test_del_frame`` the parent is a single block, we are viewing the same block in df2 even though we deleted column "b"
> The Index case is a bug at the moment, creating the df is zero copy, updating the df afterwards will propagate to the index, but will be fixed with CoW

Ah, yes, that ugly bug .. (I was assuming we didn't track some ref correctly in case of Index because of it being immutable in the non-CoW mode)

> `test_del_frame` the parent is a single block, we are viewing the same block in df2 even though we deleted column "b"

Yes, but it's still a "false positive" warning for the user. Just one we decide we can't solve? (or is not worth our time to fix)
 > Yes, but it's still a "false positive" warning for the user. Just one we decide we can't solve? (or is not worth our time to fix)

yeah sorry should have been more precise. This is a known limitation. I have no hope in coming up with a fix before 2.2 is out if ever 