Possible causes:
git log --topo-order --no-merges --oneline dcf8976a7b0f25ea326829dd4a0944d7bbe88e13..
e1b15cc (HEAD -> master, origin/master, origin/HEAD) Remove use of removed messages
e0f0b28 Remove blank translations
38d8f65 Localisation updates from https://translatewiki.net.
dde352c Adjust display to cater for diff and historical pages
0dbc0ac EntityLookupElement: Separate alias from label with a word separator
cdf6d65 Deal with cached pages with newer placeholder tags missing
628ec6f Search prototype
1bc65b3 Migrate dependencies to WikibaseCirrusSearch
5e7bda6 Localisation updates from https://translatewiki.net.
722307e Let EntityLookupElement use configured uri by default
63c8e1b Remove $wgMediaInfoShowQualifiers
bedf519 Refactor CaptionsPanel publish button refresh implementation
3f72672 Make sure there's enough space for depicts dropdown
fe8db41 MediaInfoView: revision support for getContent()