Headline shouldn't include host for https requests through proxy.

lib/http/request.rb

@@ -142,7 +142,7 @@ def connect_using_proxy(socket)
 
     # Compute HTTP request header for direct or proxy request
     def headline
-      request_uri = using_proxy? ? uri : uri.omit(:scheme, :authority)
+      request_uri = (using_proxy? && !uri.https?) ? uri : uri.omit(:scheme, :authority)
       "#{verb.to_s.upcase} #{request_uri.omit :fragment} HTTP/#{version}"
     end
 

spec/lib/http/request_spec.rb

@@ -202,6 +202,12 @@
     context "with proxy" do
       let(:proxy) { {:user => "user", :pass => "pass"} }
       it { is_expected.to eq "GET http://example.com/foo?bar=baz HTTP/1.1" }
+
+      context "and HTTPS uri" do
+        let(:request_uri) { "https://example.com/foo?bar=baz" }
+
+        it { is_expected.to eq "GET /foo?bar=baz HTTP/1.1" }
+      end
     end
   end
 end