Because I just know someone's going to complain about watchlists/RC being cluttered up by 'X bytes' instead of 'X', for the moment I'm splitting this to use the new rc-change-size message, and leave it at '$1' by default (so no change from the old behavior, showing number alone).

One could stick in the labeling if one desired, or leave it blank.

RELEASE-NOTES

@@ -462,6 +462,7 @@ it from source control: http://www.mediawiki.org/wiki/Download_from_SVN
   $wgDisableQueryPageUpdate
 * (bug 8413) Improve comments for $wgNamespaceRobotPolicies
 * (bug 8330) Show "bytes" suffix on recent changes diff counter
+  optionally... if set in rc-changes-size message (default empty for now)
 * (bug 8489) Support basic links in <gallery> caption attribute
 * (bug 8485) Correct Lingala number formatting
 * The MediaWiki namespace is no longer pre-filled with default messages on
@@ -476,6 +477,8 @@ it from source control: http://www.mediawiki.org/wiki/Download_from_SVN
 * Count deleted edits when regenerating total edits in maintenance/initStats.php
 * (bug 3706) Allow users to be exempted from IP blocks. The ipblock-exempt permission
   key has been added to enable this behaviour, by default assigned to sysops.
+
+
 == Languages updated ==
 
 * Basque (eu)

includes/RecentChange.php

@@ -581,7 +581,7 @@ class RecentChange
 		}
 
 		$szdiff = $new - $old;
-		$formatedSize = wfMsgExt( 'nbytes', array( 'parsemag', 'escape'),
+		$formatedSize = wfMsgExt( 'rc-change-size', array( 'parsemag', 'escape'),
 			$wgLang->formatNum($szdiff) );
 
 		if( $szdiff < $wgRCChangedSizeThreshold ) {

languages/messages/MessagesEn.php

@@ -1275,6 +1275,7 @@ Unselected groups will not be changed. You can deselect a group with CTRL + Left
 'number_of_watching_users_pageview' 	=> '[$1 watching user/s]',
 'rc_categories'	=> 'Limit to categories (separate with "|")',
 'rc_categories_any'	=> 'Any',
+'rc-change-size' => '$1',
 
 # Upload
 #