Add only ISO-serving mirrors as webseeds to the torrent
Contrary to what @jelle said in releng#5 (comment 24739), it appears that it's possible to list only mirrors that serve ISOs as shown by @pierre in https://github.com/pierres/archiso-manager/commit/18212cde750d94cc3dfddd07e9e3cc64607c06e9.
Running
$ curl -s 'https://archlinux.org/mirrors/status/json/' | jq -r '.urls | .[] | select( .protocol == "https" and .isos == false ) | .url'
shows that there are a few mirrors that do not serve ISOs. Adding them to the torrent is counterproductive. Torrent clients will needlessly waste bandwidth (of both parties) in effort to fetch the non-existent files.
Edited by nl6720