Index: DifferenceEngine.php
===================================================================
--- DifferenceEngine.php	(revision 18323)
+++ DifferenceEngine.php	(working copy)
@@ -523,21 +523,17 @@
 			$newLink = $this->mNewPage->escapeLocalUrl();
 			$this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
 			$newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit' );
-			$newUndo = $this->mNewPage->escapeLocalUrl( 'action=edit&undo=' . $this->mNewid );
 
 			$this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a> ($timestamp)"
-				. " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)"
-				. " (<a href='$newUndo'>" . htmlspecialchars( wfMsg( 'editundo' ) ) . "</a>)";
+				. " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
 
 		} else {
 			$newLink = $this->mNewPage->escapeLocalUrl( 'oldid=' . $this->mNewid );
 			$newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mNewid );
-			$newUndo = $this->mNewPage->escapeLocalUrl( 'action=edit&undo=' . $this->mNewid );
 			$this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $timestamp ) );
 
 			$this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>"
-				. " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)"
-				. " (<a href='$newUndo'>" . htmlspecialchars( wfMsg( 'editundo' ) ) . "</a>)";
+				. " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
 		}
 
 		// Load the old revision object
@@ -568,6 +564,9 @@
 			$oldEdit = $this->mOldPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mOldid );
 			$this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) )
 				. "</a> (<a href='$oldEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
+			//now that we considered old rev, we can make undo link (bug 8133, multi-edit undo)
+			$newUndo = $this->mNewPage->escapeLocalUrl( 'action=edit&undoafter=' . $this->mOldid . '&undoto=' . $this->mNewid);
+			$this->mNewtitle .= " (<a href='$newUndo'>" . htmlspecialchars( wfMsg( 'editundo' ) ) . "</a>)";
 		}
 
 		return true;