by adding a new configuration variable $wgApplyIpBlocksToXff (disabled by default).
=== Bug fixes in 1.21 ===
+* (bug 40617) Installer can now customize the logo in LocalSettings.php
* (bug 40353) SpecialDoubleRedirect should support interwiki redirects.
* (bug 40352) fixDoubleRedirects.php should support interwiki redirects.
* (bug 9237) SpecialBrokenRedirect should not list interwiki redirects.
* BREAKING CHANGE: The Services_JSON class has been removed; if necessary,
be sure to upgrade affected extensions at the same time (e.g. Collection).
* Calling Linker methods using a skin will now output deprecation warnings.
+* Pages with a returnto (such as the page when you login or logout), no
+ longer have a rel="next" link tag.
== Compatibility ==