Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 23297)
+++ wp-includes/post.php	(working copy)
@@ -3099,9 +3099,11 @@
 	if ( 'attachment' == $post_type ) {
 		// Attachment slugs must be unique across all types.
 		$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND ID != %d LIMIT 1";
-		$post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_ID ) );
+		$post_name_check = in_array( $slug, $feeds )
+			|| apply_filters( 'wp_unique_post_slug_is_bad_attachment_slug', false, $slug )
+			|| $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_ID ) );
 
-		if ( $post_name_check || in_array( $slug, $feeds ) || apply_filters( 'wp_unique_post_slug_is_bad_attachment_slug', false, $slug ) ) {
+		if ( $post_name_check ) {
 			$suffix = 2;
 			do {
 				$alt_post_name = substr ($slug, 0, 200 - ( strlen( $suffix ) + 1 ) ) . "-$suffix";
@@ -3116,9 +3118,12 @@
 		// Page slugs must be unique within their own trees. Pages are in a separate
 		// namespace than posts so page slugs are allowed to overlap post slugs.
 		$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type IN ( '" . implode( "', '", esc_sql( $hierarchical_post_types ) ) . "' ) AND ID != %d AND post_parent = %d LIMIT 1";
-		$post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_ID, $post_parent ) );
+		$post_name_check = in_array( $slug, $feeds )
+			|| preg_match( "@^($wp_rewrite->pagination_base)?\d+$@", $slug )
+			|| apply_filters( 'wp_unique_post_slug_is_bad_hierarchical_slug', false, $slug, $post_type, $post_parent )
+			|| $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_ID, $post_parent ) );
 
-		if ( $post_name_check || in_array( $slug, $feeds ) || preg_match( "@^($wp_rewrite->pagination_base)?\d+$@", $slug )  || apply_filters( 'wp_unique_post_slug_is_bad_hierarchical_slug', false, $slug, $post_type, $post_parent ) ) {
+		if ( $post_name_check ) {
 			$suffix = 2;
 			do {
 				$alt_post_name = substr( $slug, 0, 200 - ( strlen( $suffix ) + 1 ) ) . "-$suffix";
@@ -3130,9 +3135,14 @@
 	} else {
 		// Post slugs must be unique across all posts.
 		$check_sql = "SELECT post_name FROM $wpdb->posts WHERE post_name = %s AND post_type = %s AND ID != %d LIMIT 1";
-		$post_name_check = $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_type, $post_ID ) );
+		$post_type_obj = get_post_type_object( $post_type );
 
-		if ( $post_name_check || in_array( $slug, $feeds ) || apply_filters( 'wp_unique_post_slug_is_bad_flat_slug', false, $slug, $post_type ) ) {
+		$post_name_check = in_array( $slug, $feeds )
+			|| ( $post_type_obj->has_archive && $wp_rewrite->pagination_base == $slug )
+			|| apply_filters( 'wp_unique_post_slug_is_bad_flat_slug', false, $slug, $post_type )
+			|| $wpdb->get_var( $wpdb->prepare( $check_sql, $slug, $post_type, $post_ID ) );
+
+		if ( $post_name_check ) {
 			$suffix = 2;
 			do {
 				$alt_post_name = substr( $slug, 0, 200 - ( strlen( $suffix ) + 1 ) ) . "-$suffix";