- Issue #3094: httplib.HTTPSConnection Host: headers no longer include the

redundant ":443" port number designation when the connection is using the
  default https port (443).

Lib/httplib.py

@@ -813,7 +813,7 @@ class HTTPConnection:
                         host_enc = self.host.encode("ascii")
                     except UnicodeEncodeError:
                         host_enc = self.host.encode("idna")
-                    if self.port == HTTP_PORT:
+                    if self.port == self.default_port:
                         self.putheader('Host', host_enc)
                     else:
                         self.putheader('Host', "%s:%s" % (host_enc, self.port))

Misc/NEWS

@@ -72,6 +72,10 @@ Library
   properly when raising an exception due to the bz2file being closed.
   Prevents a deadlock.
 
+- Issue #3094: httplib.HTTPSConnection Host: headers no longer include the
+  redundant ":443" port number designation when the connection is using the
+  default https port (443).
+
 Build
 -----