This is a bug because the downside of this behaviour is outweighed by some tiny upside.
But I've never seen a person editing a bash script without an editor that swaps in a new version of the file until today, so never knowingly encountered this bug before.
I don't think that's how you define a bug. I think technically you could argue its a "logical error", however that assumes that you know the intent of the creator of bash was specifically to not allow this behavior which I don't think is the case.
But I've never seen a person editing a bash script without an editor that swaps in a new version of the file until today, so never knowingly encountered this bug before.
It should be fixed.