testutil: use dummyhost for non-tcp connections

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit e1db9e9848435042922512b3b5f6dc97f627af00)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

integration-cli/docker_api_attach_test.go

@@ -237,6 +237,11 @@ func requestHijack(method, endpoint string, data io.Reader, ct, daemon string, m
 	req.URL.Scheme = "http"
 	req.URL.Host = hostURL.Host
 
+	if hostURL.Scheme == "unix" || hostURL.Scheme == "npipe" {
+		// Override host header for non-tcp connections.
+		req.Host = client.DummyHost
+	}
+
 	for _, opt := range modifiers {
 		opt(req)
 	}

testutil/request/request.go

@@ -125,6 +125,11 @@ func newRequest(endpoint string, opts *Options) (*http.Request, error) {
 	}
 	req.URL.Host = hostURL.Host
 
+	if hostURL.Scheme == "unix" || hostURL.Scheme == "npipe" {
+		// Override host header for non-tcp connections.
+		req.Host = client.DummyHost
+	}
+
 	for _, config := range opts.requestModifiers {
 		if err := config(req); err != nil {
 			return nil, err