Specifying a custom Host header does not override default host header.

~~~
$ wrk -c 5 -t 5 -r 1000 -H 'Host: example.com' 'http://127.0.0.1:80/'
~~~

results in this:

~~~
GET / HTTP/1.1.
Host: 127.0.0.1:80.
Host: example.com.
~~~

This makes it difficult to hit test some services. Is there some other way to specify an ip to connect to vs a name to specify in the host header?