MIME type of patch files

Since a couple of days ago, when I click on a patch link in an issue, instead of displaying the patch contents Firefox will prompt me to open it with an editor or download it. Checking with wget, I saw that the file’s MIME type sent by the server is text/x-diff.

Is it possible that this changed in the last week or so? And, in either case, would it be possible to set it (back?) to text/plain instead?

It’s of course possible that this is a change in Firefox, but I couldn’t find anything about that, so I thought I’d at least try here. With Dreditor gone, having no way to open a patch file in the browser is really a bit of a bother.

Source: https://www.drupal.org/project/issues/rss/infrastructure