When uploading a file, the provided edit comment is saved for the file page history as well as the file history.

If the uploader accidentally adds private information to this field that needs to be hidden from the file history, it turns out that the file history cannot be hidden for the current file version. (This makes sense for the actual file data, but not for the comment.)
It is also not possible to upload exactly the same file to the same file page again, because this is denied for identical checksum.

So in order to achieve redacting of the upload summary one needs to upload a dummy file, revert to the original file, and the hide the comment.

It should be changed so that this can be done directly without uploading a dummy file in between.