At approximately 18:50 March 25, 2013 UTC, localization on English Wikipedia began to break down on several fields. All my examples are in Dutch, but I tested with the interface language set to Japanese and observed parallel behaviour.
- On the contribution history for an editor, "rollback" now displays as "rollback" rather than "terugdraaien". It still displays as "terugdraaien" on a watchlist.
- On the history for an article, "rollback" now displays as "rollback" rather than "terugdraaien". It still displays as "terugdraaien" on a watchlist.
- At roughly the same time, the edit tabs (for Monobook and Vector) shifted as well: "pagina" became "article", "bewerken" became "edit this page", and "+" became "add new section".
I've checked, and at this time, all of this still works on Commons.
Random fields remain localized: the dates on the contribution history remain in Dutch. The tool tips from hovering over the English fields remain in Dutch. All "history" tabs remain as "history".