`xdg-mime query filetype linux-3.2.89.tar.xz` returns nothing on artful, whereas it returns "application/x-xz-compressed-tar" on zesty, which explains why xdg-open takes a different code path.
`xdg-mime query filetype linux-3. 2.89.tar. xz` returns nothing on artful, whereas it returns "application/ x-xz-compressed -tar" on zesty, which explains why xdg-open takes a different code path.