A) Normal non-proxy HTTP:
- no more "Pragma: no-cache" (this only makes sense to proxies)
B) Non-CONNECT HTTP request over proxy:
- "Pragma: no-cache" is used (like before)
- "Proxy-Connection: Keep-alive" (for older style 1.0-proxies)
C) CONNECT HTTP request over proxy:
- "Host: [name]:[port]"
- "Proxy-Connection: Keep-alive"
replacement, curl only replaced the Host: header on the initial request
and didn't replace it on the following ones. This resulted in requests with
two Host: headers.
Now, curl checks if the location is on the same host as the initial request
and then continues to replace the Host: header. And when it moves to another
host, it doesn't replace the Host: header but it also doesn't make the
second Host: header get used in the request.
This change is verified by the two new test cases 184 and 185.
