From c490d265fa711547ff110438540b4f3457079fa2 Mon Sep 17 00:00:00 2001
From: Andrew Garrett <werdna@users.mediawiki.org>
Date: Mon, 11 Dec 2006 09:39:39 +0000
Subject: [PATCH] Per discussion on wikitech-l, add an (undo) link for on-top
 revisions as well. Also, don't do a merge if (undo) is being used for a
 straight revert

---
 includes/DifferenceEngine.php | 4 +++-
 includes/EditPage.php         | 9 +++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/includes/DifferenceEngine.php b/includes/DifferenceEngine.php
index 77fef48f9a..a72f01535f 100644
--- a/includes/DifferenceEngine.php
+++ b/includes/DifferenceEngine.php
@@ -523,9 +523,11 @@ CONTROL;
 			$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='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
+				. " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)"
+				. " (<a href='$newUndo'>" . htmlspecialchars( wfMsg( 'editundo' ) ) . "</a>)";
 
 		} else {
 			$newLink = $this->mNewPage->escapeLocalUrl( 'oldid=' . $this->mNewid );
diff --git a/includes/EditPage.php b/includes/EditPage.php
index 0d6f34b5b8..9082fd2760 100644
--- a/includes/EditPage.php
+++ b/includes/EditPage.php
@@ -109,8 +109,13 @@ class EditPage {
 					$undorev_text = $undorev->getText();
 					$oldrev_text = $oldrev->getText();
 					$currev_text = $text;
-	
-					$result = wfMerge($undorev_text, $oldrev_text, $currev_text, $text);
+
+					#No use doing a merge if it's just a straight revert.
+					if ($currev_text != $undorev_text) {
+						$result = wfMerge($undorev_text, $oldrev_text, $currev_text, $text);
+					} else {
+						$result = true;
+					}
 	
 					if (!$result) {
 						#Undoing failed. Bailing out with regular revision text.
-- 
2.20.1