Ticket #22378: 22378.3.diff

src/wp-admin/includes/class-wp-upgrader.php

@@ -108 +108 @@
 
         function download_package($package) {
 
+                /**
+                 * Filter whether to return the package.
+                 *
+                 * @since 3.7.0
+                 *
+                 * @param bool    $reply   Whether to bail without returning the package. Default is false.
+                 * @param string  $package The package file name.
+                 * @param object  $this    The WP_Upgrader instance.
+                 */
+                $reply = apply_filters( 'upgrader_pre_download', false, $package, $this );
+                if ( false !== $reply )
+                        return $reply;
+
                 if ( ! preg_match('!^(http|https|ftp)://!i', $package) && file_exists($package) ) //Local file or remote?
                         return $package; //must be a local file..