Address some review feedback

Author: barneygale

Doc/library/pathlib.rst

@@ -872,11 +872,10 @@ conforming to :rfc:`8089`.
    .. versionadded:: 3.13
 
    .. versionchanged:: next
-      If a URL authority (e.g. a hostname) is present and resolves to
-      ``localhost``, it is discarded. If an authority is present and
-      *doesn't* resolve to ``localhost``, then on Windows a UNC path is
-      returned (as before), and on other platforms a :exc:`ValueError` is
-      raised.
+      If a URL authority (e.g. a hostname) is present and resolves to a local
+      address, it is discarded. If an authority is present and *doesn't*
+      resolve to a local address, then on Windows a UNC path is returned (as
+      before), and on other platforms a :exc:`ValueError` is raised.
 
 .. method:: Path.as_uri()
 

Doc/library/urllib.request.rst

@@ -182,11 +182,10 @@ The :mod:`urllib.request` module defines the following functions:
       'C:\\Program Files'
 
    .. versionchanged:: next
-      If a URL authority (e.g. a hostname) is present and resolves to
-      ``localhost``, it is discarded. If an authority is present and
-      *doesn't* resolve to ``localhost``, then on Windows a UNC path is
-      returned (as before), and on other platforms a
-      :exc:`~urllib.error.URLError` is raised.
+      If a URL authority (e.g. a hostname) is present and resolves to a local
+      address, it is discarded. If an authority is present and *doesn't*
+      resolve to a local address, then on Windows a UNC path is returned (as
+      before), and on other platforms :exc:`~urllib.error.URLError` is raised.
 
    .. versionchanged:: 3.14
       Windows drive letters are no longer converted to uppercase, and ``:``

Doc/whatsnew/3.14.rst

@@ -1002,7 +1002,7 @@ urllib
 
   In :func:`urllib.request.url2pathname`:
 
-  - Discard URL authorities that resolve to ``localhost``.
+  - Discard URL authorities that resolve to a local address.
   - Raise :exc:`~urllib.error.URLError` if a URL authority doesn't resolve
     to ``localhost``, except on Windows where we return a UNC path.
 

Lib/urllib/request.py

@@ -1483,11 +1483,11 @@ def _is_local_authority(authority):
         return False
     if _local_addresses is None:
         try:
-            _local_addresses = tuple(
+            _local_addresses = frozenset(
                 socket.gethostbyname_ex('localhost')[2] +
                 socket.gethostbyname_ex(socket.gethostname())[2])
         except socket.gaierror:
-            _local_addresses = (socket.gethostbyname('localhost'),)
+            _local_addresses = frozenset(socket.gethostbyname('localhost'),)
     return address in _local_addresses
 
 class FTPHandler(BaseHandler):