Index: wp-admin/edit.php
===================================================================
--- wp-admin/edit.php	(revision 19071)
+++ wp-admin/edit.php	(working copy)
@@ -9,15 +9,11 @@
 /** WordPress Administration Bootstrap */
 require_once( './admin.php' );
 
-if ( !isset($_GET['post_type']) )
-	$post_type = 'post';
-elseif ( in_array( $_GET['post_type'], get_post_types( array('show_ui' => true ) ) ) )
-	$post_type = $_GET['post_type'];
-else
+$post_type = isset( $_GET['post_type'] ) ? $_GET['post_type'] : 'post';
+
+if ( ! in_array( $post_type, get_post_types( array('show_ui' => true ) ) ) )
 	wp_die( __('Invalid post type') );
 
-$_GET['post_type'] = $post_type;
-
 $post_type_object = get_post_type_object( $post_type );
 
 if ( !current_user_can($post_type_object->cap->edit_posts) )