+
+ // If Last-Modified is set to false, it should not be sent (no-cache situation).
+ if ( isset( $headers['Last-Modified'] ) && false === $headers['Last-Modified'] ) {
+ unset( $headers['Last-Modified'] );
+
+ // In PHP 5.3+, make sure we are not sending a Last-Modified header.
+ if ( function_exists( 'header_remove' ) ) {
+ @header_remove( 'Last-Modified' );
+ } else {
+ // In PHP 5.2, send an empty Last-Modified header, but only as a
+ // last resort to override a header already sent. #WP23021
+ foreach ( headers_list() as $header ) {
+ if ( 0 === stripos( $header, 'Last-Modified' ) ) {
+ $headers['Last-Modified'] = '';
+ break;
+ }
+ }
+ }
+ }
+