Change standalone header when in mirroring mode (prevents client from sending basic auth headers and overwriting token)

Author: shin-

docker_registry/app.py

@@ -27,9 +27,10 @@
 @app.route('/_ping')
 @app.route('/v1/_ping')
 def ping():
-    return toolkit.response(headers={
-        'X-Docker-Registry-Standalone': cfg.standalone is not False
-    })
+    headers = {'X-Docker-Registry-Standalone': cfg.standalone is not False}
+    if cfg.mirroring:
+        headers['X-Docker-Registry-Standalone'] = 'mirror'
+    return toolkit.response(headers=headers)
 
 
 @app.route('/')