Index: src/wp-includes/ms-functions.php
===================================================================
--- src/wp-includes/ms-functions.php	(revision 27063)
+++ src/wp-includes/ms-functions.php	(working copy)
@@ -277,6 +277,10 @@
 		$reassign = (int) $reassign;
 		$wpdb->query( $wpdb->prepare("UPDATE $wpdb->posts SET post_author = %d WHERE post_author = %d", $reassign, $user_id) );
 		$wpdb->query( $wpdb->prepare("UPDATE $wpdb->links SET link_owner = %d WHERE link_owner = %d", $reassign, $user_id) );
+
+		// clean post cache for reassigned posts
+		$post_ids = $wpdb->get_col( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE post_author = %d", $reassign ) );
+		array_map( 'clean_post_cache', $post_ids );
 	}
 
 	restore_current_blog();