Last modified: 2014-04-29 19:24:38 UTC
They seem to only have the latest releases, not the past releases.
We don't care about 1.20 anymore (unsupported), but https://releases.wikimedia.org/mediawiki/1.19/ provides only 1.19.9 and newer.
Doesn't matter that it's unsupported, it's for historical reasons anyway. Technically all of the missing dot releases are no longer supported.