bpo-26589: Add http status code 451 (GH-15413)

Doc/library/http.rst

@@ -106,6 +106,7 @@ Code    Enum Name                           Details
 ``428`` ``PRECONDITION_REQUIRED``           Additional HTTP Status Codes :rfc:`6585`
 ``429`` ``TOO_MANY_REQUESTS``               Additional HTTP Status Codes :rfc:`6585`
 ``431`` ``REQUEST_HEADER_FIELDS_TOO_LARGE`` Additional HTTP Status Codes :rfc:`6585`
+``451`` ``UNAVAILABLE_FOR_LEGAL_REASONS``   An HTTP Status Code to Report Legal Obstacles :rfc:`7725`
 ``500`` ``INTERNAL_SERVER_ERROR``           HTTP/1.1 :rfc:`7231`, Section 6.6.1
 ``501`` ``NOT_IMPLEMENTED``                 HTTP/1.1 :rfc:`7231`, Section 6.6.2
 ``502`` ``BAD_GATEWAY``                     HTTP/1.1 :rfc:`7231`, Section 6.6.3
@@ -126,3 +127,6 @@ equal to the constant name (i.e. ``http.HTTPStatus.OK`` is also available as
 
 .. versionchanged:: 3.7
    Added ``421 MISDIRECTED_REQUEST`` status code.
+
+.. versionadded:: 3.8
+   Added ``451 UNAVAILABLE_FOR_LEGAL_REASONS`` status code.

Lib/http/__init__.py

@@ -15,6 +15,7 @@ class HTTPStatus(IntEnum):
         * RFC 7238: Permanent Redirect
         * RFC 2295: Transparent Content Negotiation in HTTP
         * RFC 2774: An HTTP Extension Framework
+        * RFC 7725: An HTTP Status Code to Report Legal Obstacles
         * RFC 7540: Hypertext Transfer Protocol Version 2 (HTTP/2)
     """
     def __new__(cls, value, phrase, description=''):
@@ -114,6 +115,10 @@ class HTTPStatus(IntEnum):
         'Request Header Fields Too Large',
         'The server is unwilling to process the request because its header '
         'fields are too large')
+    UNAVAILABLE_FOR_LEGAL_REASONS = (451,
+        'Unavailable For Legal Reasons',
+        'The server is denying access to the '
+        'resource as a consequence of a legal demand')
 
     # server errors
     INTERNAL_SERVER_ERROR = (500, 'Internal Server Error',

Lib/test/test_httplib.py

@@ -1401,6 +1401,7 @@ class OfflineTest(TestCase):
             'PRECONDITION_REQUIRED',
             'TOO_MANY_REQUESTS',
             'REQUEST_HEADER_FIELDS_TOO_LARGE',
+            'UNAVAILABLE_FOR_LEGAL_REASONS',
             'INTERNAL_SERVER_ERROR',
             'NOT_IMPLEMENTED',
             'BAD_GATEWAY',

Misc/NEWS.d/next/Library/2019-08-23-00-55-19.bpo-26589.M1xyxG.rst

+Added a new status code to the http module: 451
+UNAVAILABLE_FOR_LEGAL_REASONS