Ticket #26735: 26735.2.diff

src/wp-admin/includes/plugin.php

@@ -920 +920 @@
                 }
                 unset($uninstallable_plugins);
 
-                define('WP_UNINSTALL_PLUGIN', $file);
+                if ( ! defined( 'WP_UNINSTALL_PLUGIN' ) ) {
+                        define( 'WP_UNINSTALL_PLUGIN', true );
+                }
                 include WP_PLUGIN_DIR . '/' . dirname($file) . '/uninstall.php';
 
                 return true;