* $wgCdnMaxageLagged was added, which limits the CDN cache TTL
when any load balancer uses a DB that is lagged beyond the 'max lag'
setting in the relevant section of $wgLBFactoryConf.
+* Added several JavaScript libraries for uploading files to MediaWiki
+ from the client-side. See documentation for mw.Upload and its
+ subclasses for more information.
+* Added OOUI dialogs and layout for file upload interfaces. See
+ documentation for mw.Upload.Dialog, mw.Upload.BookletLayout and its
+ subclasses for more information.
==== External libraries ====
=== Action API changes in 1.27 ===
* Added list=allrevisions.
* generator=recentchanges now has the option to generate revids.
+* ApiPageSet::setRedirectMergePolicy() was added. This allows generator
+ modules to define how generator data for a redirect source gets merged
+ into the redirect destination.
+* prop=imageinfo&iiprop=uploadwarning will no longer include the possibility of
+ "was-deleted" warning.
=== Action API internal changes in 1.27 ===