Define a "session_id_context" at context creation. This is recommended
for the OpenSSL server-side session cache.
diff --git a/Modules/_ssl.c b/Modules/_ssl.c
index 4f7bb4d..499ecba 100644
--- a/Modules/_ssl.c
+++ b/Modules/_ssl.c
@@ -1478,6 +1478,11 @@
     SSL_CTX_set_verify(self->ctx, SSL_VERIFY_NONE, NULL);
     SSL_CTX_set_options(self->ctx, SSL_OP_ALL);
 
+#define SID_CTX "Python"
+    SSL_CTX_set_session_id_context(self->ctx, (const unsigned char *) SID_CTX,
+                                   sizeof(SID_CTX));
+#undef SID_CTX
+
     return (PyObject *)self;
 }