appending .tar.gz to archive URL causes 503 #365

works:

https://tangled.org/zzstoatzz.io/zat/archive/main

doesn't work (returns 503 HTML with 200 status):

https://tangled.org/zzstoatzz.io/zat/archive/main.tar.gz

github uses /archive/main.tar.gz, so users trying that pattern get a 503 HTML page.

repro:

# 503 as HTML, but 200 status
curl -sL "https://tangled.org/zzstoatzz.io/zat/archive/main.tar.gz" | file -

# works
curl -sL "https://tangled.org/zzstoatzz.io/zat/archive/main" | file -

supporting the .tar.gz extension would help users coming from github who expect that pattern.