* Add req.host to targetURL when redirecting to https
The req.URL.Host might not be present when redirecting to https if the
given req.URL is something like "/". In such scenario, the req.Host is
still present and valid.
This commit adds the original req.Host to the targetURL before returning
the 308 status, to avoid having a `Location: https:///` in the response.
* Bring back empty line
* Wrap the setting of targetURL.Host in a condition
* Add a comment to the test explaining why the redirectURL includes example.com
* Add changelog entry
a999270cf3