--- Python-3.10.0rc2/Lib/http/client.py	2021-09-07 21:18:28.000000000 +0800
+++ Python-3.10.0rc2/Lib/http/client.py	2021-09-30 10:22:31.513921004 +0800
@@ -70,6 +70,7 @@
 
 import email.parser
 import email.message
+import errno
 import http
 import io
 import re
@@ -939,7 +940,12 @@
         sys.audit("http.client.connect", self, self.host, self.port)
         self.sock = self._create_connection(
             (self.host,self.port), self.timeout, self.source_address)
-        self.sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+        # Might fail in OSs that don't implement TCP_NODELAY
+        try:
+             self.sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+        except OSError as e:
+            if e.errno != errno.ENOPROTOOPT:
+                raise
 
         if self._tunnel_host:
             self._tunnel()