CVE-2023-23914: curl HSTS ignored on multiple requests

How it was found

Summary:

curl tool HSTS doesn't work correctly when performing multiple requests within a single invocation.

Steps To Reproduce:

1. curl --hsts "" https://hsts.example.com http://hsts.example.com

The second request will be performed over HTTP regardless if correct HSTS header is returned by the first request.

Impact

Request performed over insecure channels unexpectedly and loss of confidentiality and integrity.