Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 8479)
+++ wp-includes/post.php	(working copy)
@@ -3113,7 +3113,6 @@
 		// Allow these to be versioned
 		$fields = array(
 			'post_title' => __( 'Title' ),
-			'post_author' => __( 'Author' ),
 			'post_content' => __( 'Content' ),
 			'post_excerpt' => __( 'Excerpt' ),
 		);
@@ -3122,7 +3121,7 @@
 		$fields = apply_filters( '_wp_post_revision_fields', $fields );
 
 		// WP uses these internally either in versioning or elsewhere - they cannot be versioned
-		foreach ( array( 'ID', 'post_name', 'post_parent', 'post_date', 'post_date_gmt', 'post_status', 'post_type', 'comment_count' ) as $protect )
+		foreach ( array( 'ID', 'post_name', 'post_parent', 'post_date', 'post_date_gmt', 'post_status', 'post_type', 'comment_count', 'post_author' ) as $protect )
 			unset( $fields[$protect] );
 	}
 
Index: wp-admin/revision.php
===================================================================
--- wp-admin/revision.php	(revision 8479)
+++ wp-admin/revision.php	(working copy)
@@ -134,9 +134,6 @@
 	$title = __( 'Post Revisions' );
 }
 
-// Converts post_author ID# into name
-add_filter( '_wp_post_revision_field_post_author', 'get_author_name' );
-
 require_once( 'admin-header.php' );
 
 ?>