Return a 409 Conflict instead of a 200 OK on an edit conflict when saving a page in the save action

Changelog.md

@@ -14,6 +14,7 @@ This file holds the changelog for Pepperminty Wiki. This is the master list of t
 
 ### Changed
  - Display returnto URL above the login form if present to further mitigate CSRF issues
+ - [Rest API] Return a 409 Conflict instead of a 200 OK on an edit conflict when saving a page in the `save` action
 
 ### Fixed
  - Stats: Fix crash when loading the stats page

modules/page-edit.php

@@ -503,6 +503,7 @@ DIFFSCRIPT;
 					page_renderer::add_js_link("$paths->extra_data_directory/page-edit/diff.min.js");
 					page_renderer::add_js_snippet($diff_script);
 					
+					http_response_code(409);
 					header("x-failure-reason: edit-conflict");
 					exit(page_renderer::render_main("Edit Conflict - $env->page - $settings->sitename", $content));
 				}