Index: trunk/src/wp-includes/comment.php
===================================================================
--- trunk/src/wp-includes/comment.php	(revision 27582)
+++ trunk/src/wp-includes/comment.php	(working copy)
@@ -394,7 +394,9 @@
 			$clauses = $this->meta_query->get_sql( 'comment', $wpdb->comments, 'comment_ID', $this );
 			$join .= $clauses['join'];
 			$where .= $clauses['where'];
-			$groupby = "{$wpdb->comments}.comment_ID";
+			if ( ! $count ) {
+				$groupby = "{$wpdb->comments}.comment_ID";
+			}
 		}
 
 		if ( ! empty( $date_query ) && is_array( $date_query ) ) {