$ rg 'UPDATE_URL|VERSION_URL'
  youtube_dl/update.py
  35:    UPDATE_URL = 'https://yt-dl.org/update/'
  36:    VERSION_URL = UPDATE_URL + 'LATEST_VERSION'
  37:    JSON_URL = UPDATE_URL + 'versions.json'
  46:        newversion =  opener.open(VERSION_URL).read().decode('utf-8').strip()

  $ curl -IL https://yt-dl.org/update/LATEST_VERSION
  HTTP/1.1 302 Found
  Date: Fri, 23 Oct 2020 20:15:04 GMT
  Server: Apache/2.2.15 (CentOS)
  Location: https://ytdl-org.github.io/youtube-dl/update/LATEST_VERSION
  Connection: close
  Content-Type: text/html; charset=iso-8859-1

  HTTP/2 404
  content-type: text/html; charset=utf-8
  server: GitHub.com
  etag: "5f777b31-239b"
  content-security-policy: default-src 'none'; style-src 'unsafe-inline'; img-src data:; connect-src 'self'
  x-github-request-id: 170E:2B71:1A0B5DC:1B8177E:5F933973
  accept-ranges: bytes
  date: Fri, 23 Oct 2020 20:15:04 GMT
  via: 1.1 varnish
  age: 85
  x-served-by: cache-hnd18722-HND
  x-cache: HIT
  x-cache-hits: 1
  x-timer: S1603484104.479172,VS0,VE0
  vary: Accept-Encoding
  x-fastly-request-id: a7128dab84232184052e51f07eb6263f5c88ab7e
  content-length: 9115