disable middlebox_comp_mode in mix httpc

Author: ruslandoga

lib/mix/lib/mix/utils.ex

@@ -738,11 +738,21 @@ defmodule Mix.Utils do
         file -> {:cacertfile, file}
       end
 
-    # Use the system certificates
+    # disable middlebox compatibility mode by default
+    # but allow it to be enabled via an environment variable
+    # see https://github.com/elixir-lang/elixir/issues/14356
+    middlebox_comp_mode =
+      case System.get_env("HEX_MIDDLEBOX_COMP_MODE") do
+        t when t in ["true", "t", "yes", "y", "1"] -> true
+        _ -> false
+      end
+
+    # Use the system certificates and set the middlebox compatibility mode
     ssl_options = [
       cacert_opt,
       verify: :verify_peer,
-      customize_hostname_check: [match_fun: :public_key.pkix_verify_hostname_match_fun(:https)]
+      customize_hostname_check: [match_fun: :public_key.pkix_verify_hostname_match_fun(:https)],
+      middlebox_comp_mode: middlebox_comp_mode
     ]
 
     # We are using relaxed: true because some servers is returning a Location