rearrange methodcaller_new so that the main error case does not cause uninitialized memory usage (closes #27783)

Reported by Thomas E. Hybel

Reported by Thomas E. Hybel

Ignore the HTTP_PROXY variable when REQUEST_METHOD environment is set, which
indicates that the script is in CGI mode.

Issue #27568 Reported and patch contributed by Rémi Rampin.

Ignore the HTTP_PROXY variable when REQUEST_METHOD environment is set, which
indicates that the script is in CGI mode.

Issue #27568 Reported and patch contributed by Rémi Rampin.

This backports the fix from #16611, per discussion with the release
manager.