It has now been backported [1] to the currently supported MediaWiki
branches: REL1_27, REL1_31 and REL1_32 [2].
[1]
https://gerrit.wikimedia.org/r/q/I61a5e68e74176f9f25bddf154eb100b224a018f5
[2]
https://www.mediawiki.org/wiki/Version_lifecycle
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Bartosz Dziewoński