can't change content-type with-out reupload

The cf-devguide specifically says:
"You cannot use the POST operation to change any of the Object's other headers such as Content-Type, ETag, etc."

But it seems like it'd be nice if you could.

In fact more generally it seems practical to allow for the end user to update SOME of the header values sent in the response without having to re-upload the file. (e.g. Content-Type, Content-Encoding, Expires, etc.)

Perhaps we define a convention that allows the user to POST "magic X-Override" keys, which are saved in the .meta file - and appended to the header of the response, overriding allowed header fields, and excluding those which we've disallowed.

e.g.
"X-Override-Content-Type"