stop setting root_url for offical taps' bottles

Library/Homebrew/cmd/bottle.rb

@@ -9,7 +9,7 @@ require 'extend/pathname'
 
 BOTTLE_ERB = <<-EOS
   bottle do
-    <% if  root_url != BottleSpecification::DEFAULT_ROOT_URL %>
+    <% if  !root_url.start_with?(BottleSpecification::DEFAULT_DOMAIN) %>
     root_url "<%= root_url %>"
     <% end  %>
     <% if  prefix != BottleSpecification::DEFAULT_PREFIX %>

Library/Homebrew/cmd/test-bot.rb

@@ -486,9 +486,6 @@ module Homebrew
       if install_passed
         if formula.stable? && !ARGV.include?('--no-bottle')
           bottle_args = ["--rb", canonical_formula_name]
-          if @tap
-            bottle_args << "--root-url=#{BottleSpecification::DEFAULT_DOMAIN}/#{Bintray.repository(@tap)}"
-          end
           bottle_args << { :puts_output_on_success => true }
           test "brew", "bottle", *bottle_args
           bottle_step = steps.last