Index: includes/parser/Parser.php
===================================================================
--- includes/parser/Parser.php	(revision 60487)
+++ includes/parser/Parser.php	(working copy)
@@ -2052,15 +2052,33 @@
 			// If we have no prefixes, go to paragraph mode.
 			if( 0 == $prefixLength ) {
 				wfProfileIn( __METHOD__."-paragraph" );
-				# No prefix (not in list)--go to paragraph mode
 				// XXX: use a stack for nestable elements like span, table and div
-				$openmatch = preg_match('/(?:<table|<blockquote|<h1|<h2|<h3|<h4|<h5|<h6|<pre|<tr|<p|<ul|<ol|<li|<\\/tr|<\\/td|<\\/th)/iS', $t );
+				// Note: <div> is matched by closematch not openmatch therefore
+				// $inBlockElem == false
+				$openblock = array();
+				$openmatch = preg_match('/(?:<table|<blockquote|<h1|<h2|<h3|<h4|<h5|<h6|<pre|<tr|<p|<ul|<ol|<li|<\\/tr|<\\/td|<\\/th)/iS', 
+					$t, $openblock, PREG_OFFSET_CAPTURE);
+				$closeblock = array();
 				$closematch = preg_match(
 					'/(?:<\\/table|<\\/blockquote|<\\/h1|<\\/h2|<\\/h3|<\\/h4|<\\/h5|<\\/h6|'.
-					'<td|<th|<\\/?div|<hr|<\\/pre|<\\/p|'.$this->mUniqPrefix.'-pre|<\\/li|<\\/ul|<\\/ol|<\\/?center)/iS', $t );
+					'<td|<th|<\\/?div|<hr|<\\/pre|<\\/p|'.$this->mUniqPrefix.'-pre|<\\/li|<\\/ul|<\\/ol|<\\/?center)/iS', 
+					$t, $closeblock, PREG_OFFSET_CAPTURE);
 				if ( $openmatch or $closematch ) {
 					$paragraphStack = false;
-					# TODO bug 5718: paragraph closed
+					#TODO bug 5718: paragraph closed
+					$tagstart = -1;
+					if ($openmatch) {
+						$tagstart = $openblock[0][1];
+					} else {
+						$tagstart = $closeblock[0][1];
+					}
+					if (!preg_match('/<\\/?div/', $t)) {
+						// FIXME: Handle div as a special case to stay 
+						// consistent with old behavior after fixing 
+						// bug 5718, but div processing needs to be fixed.
+						$output .= substr($t, 0, $tagstart);
+						$t = substr($t, $tagstart);
+					}
 					$output .= $this->closeParagraph();
 					if ( $preOpenMatch and !$preCloseMatch ) {
 						$this->mInPre = true;
@@ -2089,6 +2107,9 @@
 							} else {
 								if ($this->mLastSection !== 'p' ) {
 									$output .= $this->closeParagraph();
+									// FIXME: closeParagraph will clear 
+									// mLastSection. Don't need to do that in
+									// both places.
 									$this->mLastSection = '';
 									$paragraphStack = '<p>';
 								} else {