std.net.curl and HTTP.responseHeaders

[Vindex via Digitalmars-d-learn]

Header requests to Wikipedia give 405 error for some reason.

```
import std.stdio, std.net.curl;

void main() {
    auto url = "https://en.wikipedia.org/wiki/Passenger_pigeon";;
    auto http = HTTP();
    options(url, http);
    writeln(http.responseHeaders);
}
```


Output:
```
std.net.curl.HTTPStatusException@/usr/include/dmd/phobos/std/net/curl.d(1097): 
HTTP request returned status code 405 ()
```

Perhaps some special HTTP configuration is needed?