Comment 1 for bug 179983

The mime-type of the attachment is set at upload time, using the mime-type that the uploading browser claims the file to be when POSTing.

So the problem is that the browser that uploaded it is setting the wrong mime-type, and Launchpad is then faithfully serving it as the mime-type it was told to.

So I don't think this is a Launchpad bug (although perhaps it would be useful for the person uploading the attachment to be able to override the mime-type that a browser auto-detects?).

(Btw, an encoding of "gzip" would be wrong here: the file itself is gzipped, as indicated by the "z" in "svgz". So its not just a transfer encoding, it's the actual content of the file. It would be wrong to tell the receiving browser that the file extension is "svgz", but then tell it to ungzip the contents before saving them, which is what your proposed Apache directives would do.)