Fix test.test_support.bind_port() to not cause an error when Python was

compiled on a system with SO_REUSEPORT defined in the headers but run on
a system with an OS kernel that does not support that new socket option.

Lib/test/test_support.py

@@ -409,9 +409,15 @@ def bind_port(sock, host=HOST):
                 raise TestFailed("tests should never set the SO_REUSEADDR "   \
                                  "socket option on TCP/IP sockets!")
         if hasattr(socket, 'SO_REUSEPORT'):
-            if sock.getsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT) == 1:
-                raise TestFailed("tests should never set the SO_REUSEPORT "   \
-                                 "socket option on TCP/IP sockets!")
+            try:
+                if sock.getsockopt(socket.SOL_SOCKET, socket.SO_REUSEPORT) == 1:
+                    raise TestFailed("tests should never set the SO_REUSEPORT "   \
+                                     "socket option on TCP/IP sockets!")
+            except EnvironmentError:
+                # Python's socket module was compiled using modern headers
+                # thus defining SO_REUSEPORT but this process is running
+                # under an older kernel that does not support SO_REUSEPORT.
+                pass
         if hasattr(socket, 'SO_EXCLUSIVEADDRUSE'):
             sock.setsockopt(socket.SOL_SOCKET, socket.SO_EXCLUSIVEADDRUSE, 1)
 

Misc/NEWS

@@ -12,6 +12,10 @@ Core and Builtins
 Library
 -------
 
+- Fix test.test_support.bind_port() to not cause an error when Python was
+  compiled on a system with SO_REUSEPORT defined in the headers but run on
+  a system with an OS kernel that does not support that new socket option.
+
 - Issue #19633: Fixed writing not compressed 16- and 32-bit wave files on
   big-endian platforms.