Fixed #20598 -- Add new HTTP status codes defined in rfc6585

428, 429, 431 and 511

django/http/response.py

@@ -66,6 +66,9 @@ REASON_PHRASES = {
     423: 'LOCKED',
     424: 'FAILED DEPENDENCY',
     426: 'UPGRADE REQUIRED',
+    428: 'PRECONDITION REQUIRED',
+    429: 'TOO MANY REQUESTS',
+    431: 'REQUEST HEADER FIELDS TOO LARGE',
     500: 'INTERNAL SERVER ERROR',
     501: 'NOT IMPLEMENTED',
     502: 'BAD GATEWAY',
@@ -76,6 +79,7 @@ REASON_PHRASES = {
     507: 'INSUFFICIENT STORAGE',
     508: 'LOOP DETECTED',
     510: 'NOT EXTENDED',
+    511: 'NETWORK AUTHENTICATION REQUIRED',
 }