Fixed following of internal redirects when using a custom Host header

Webrat didn't properly follow internal redirects when using the Host
  header, this lets Webrat check the Host header before falling back
  to www.example.com as the current_host.

lib/webrat/core/session.rb

@@ -264,7 +264,7 @@ For example:
     end
 
     def current_host
-      URI.parse(current_url).host || "www.example.com"
+      URI.parse(current_url).host || @custom_headers["Host"] || "www.example.com"
     end
 
     def response_location_host

spec/integration/rails/app/controllers/webrat_controller.rb

@@ -25,6 +25,10 @@ class WebratController < ApplicationController
     redirect_to "http://google.com"
   end
 
+  def host_redirect
+    redirect_to submit_url
+  end
+
   def before_redirect_form
   end
 

spec/integration/rails/config/routes.rb

@@ -4,6 +4,7 @@ ActionController::Routing::Routes.draw do |map|
     webrat.internal_redirect  "/internal_redirect", :action => "internal_redirect"
     webrat.external_redirect  "/external_redirect", :action => "external_redirect"
     webrat.infinite_redirect  "/infinite_redirect", :action => "infinite_redirect"
+    webrat.host_redirect      "/host_redirect",     :action => "host_redirect"
 
     webrat.before_redirect_form     "/before_redirect_form",    :action => "before_redirect_form"
     webrat.redirect_to_show_params  "/redirect_to_show_params", :action => "redirect_to_show_params"

spec/integration/rails/test/integration/webrat_test.rb

@@ -45,6 +45,13 @@ class WebratTest < ActionController::IntegrationTest
     assert response.redirect?
   end
 
+  test "should recognize the host header to follow redirects properly" do
+    header "Host", "foo.bar"
+    visit host_redirect_path
+    assert !response.redirect?
+    assert response.body.include?("OK")
+  end
+
   test "should click link by text" do
     visit internal_redirect_path
     click_link "Test Link Text"