https://github.com/boto/boto/commit/b9f6cb0ab717ea76e2780c7fddd1cd36b3bf7d63

From b9f6cb0ab717ea76e2780c7fddd1cd36b3bf7d63 Mon Sep 17 00:00:00 2001
From: Matt Houglum <houglum@google.com>
Date: Fri, 21 Jun 2019 15:09:11 -0700
Subject: [PATCH] Make server_name() behave correctly for PY3

...because Python-2.6-or-newer doesn't just include Python 2.6 and 2.7.
---
 boto/connection.py | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/boto/connection.py b/boto/connection.py
index 54e26fb2de16..bbb25d8fb842 100644
--- a/boto/connection.py
+++ b/boto/connection.py
@@ -650,17 +650,13 @@ class AWSAuthConnection(object):
         if port == 80:
             signature_host = self.host
         else:
-            # This unfortunate little hack can be attributed to
-            # a difference in the 2.6 version of http_client.  In old
-            # versions, it would append ":443" to the hostname sent
-            # in the Host header and so we needed to make sure we
-            # did the same when calculating the V2 signature.  In 2.6
-            # (and higher!)
-            # it no longer does that.  Hence, this kludge.
-            if ((ON_APP_ENGINE and sys.version[:3] == '2.5') or
-                    sys.version[:3] in ('2.6', '2.7')) and port == 443:
+            ver_int = sys.version_info[0] * 10 + sys.version_info[1]
+            if port == 443 and ver_int >= 26:  # Py >= 2.6
                 signature_host = self.host
             else:
+                # In versions < 2.6, Python's http_client would append ":443"
+                # to the hostname sent in the Host header and so we needed to
+                # make sure we did the same when calculating the V2 signature.
                 signature_host = '%s:%d' % (self.host, port)
         return signature_host
 
-- 
2.28.0