Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 18974)
+++ wp-includes/post.php	(working copy)
@@ -2440,10 +2440,20 @@
 	}
 
 	if ( ('' == $post_content) && ('' == $post_title) && ('' == $post_excerpt) && ('attachment' != $post_type) ) {
-		if ( $wp_error )
-			return new WP_Error('empty_content', __('Content, title, and excerpt are empty.'));
-		else
+		if ( $wp_error ) {
+			if ( post_type_supports( $post_type, 'title' ) && post_type_supports( $post_type, 'excerpt' ) )
+				$message = __( 'Content, title, and excerpt are empty.' );
+			elseif ( post_type_supports( $post_type, 'title' ) )
+				$message = __( 'Content and title are empty.' );
+			elseif ( post_type_supports( $post_type, 'excerpt' ) )
+				$message = __( 'Content and excerpt are empty.' );
+			else
+				$message = __( 'Content is empty.' );
+
+			return new WP_Error( 'empty_content', $message );
+		} else {
 			return 0;
+		}
 	}
 
 	if ( empty($post_type) )