Comment 9 for bug 1849684

I can see the issue is due to bug in:
main/scripts/casper-bottom/24preseed, line 72
preseed/url=*|url=*)
  url_location="${x#url=}"
  start_network
  chroot /root wget -P /tmp "$url_location"
  locations="/tmp/$(basename "$url_location") $locations"
  ;;

if you specific
preseed/url=http://host/path/to/preseed.cfg
the variable url_location will not be transformed correctly, it will just as "preseed/url=http://host/path/to/preseed.cfg"

however, for
url=http://host/path/to/preseed.cfg
then url_location see correctly to
"http://host/path/to/preseed.cfg"