* Added a new hook, 'TitleMoveCompleting', which runs before a page move is committed.
* $wgCdnReboundPurgeDelay was added to provide secondary delayed purges of URLs
from CDN to mitigate DB replication lag and WAN cache purge lag.
+* (T49162) Installer will default to setting CACHE_ACCEL as the main cache type
+ if it is available.
=== External library changes in 1.27 ===
==== Upgraded external libraries ====
* wfMsgNoTrans() was removed (deprecated since 1.18).
* Linker::makeImageLink2 was removed (deprecated since 1.20).
* Title::userIsWatching() was removed (deprecated since 1.20).
+* Removed WaitForSlave maintenance script; use SELECT MASTER_POS_WAIT()
+ database function directly instead.
+* wfMsg() was removed (deprecated since 1.18).
+* wfMsgForContent() was removed (deprecated since 1.18).
+* wfMsgReal() was removed (deprecated since 1.18).
+* wfMsgGetKey() was removed (deprecated since 1.18).
+* wfMsgHtml() was removed (deprecated since 1.18).
+* wfMsgWikiHtml() was removed (deprecated since 1.18).
+* wfMsgExt() was removed (deprecated since 1.18).
== Compatibility ==