Don't push siblings on load path if using bundled env

actionmailer/test/abstract_unit.rb

+bundled = "#{File.dirname(__FILE__)}/../vendor/gems/environment"
+if File.exist?("#{bundled}.rb")
+  require bundled
+else
+  $:.unshift "#{File.dirname(__FILE__)}/../../activesupport/lib"
+  $:.unshift "#{File.dirname(__FILE__)}/../../actionpack/lib"
+end
+
 require 'rubygems'
 require 'test/unit'
 
 $:.unshift "#{File.dirname(__FILE__)}/../lib"
-$:.unshift "#{File.dirname(__FILE__)}/../../activesupport/lib"
-$:.unshift "#{File.dirname(__FILE__)}/../../actionpack/lib"
 require 'action_mailer'
 require 'action_mailer/test_case'
 

actionpack/test/abstract_unit.rb

+bundled = "#{File.dirname(__FILE__)}/../vendor/gems/environment"
+if File.exist?("#{bundled}.rb")
+  require bundled
+else
+  $:.unshift "#{File.dirname(__FILE__)}/../../activesupport/lib"
+  $:.unshift "#{File.dirname(__FILE__)}/../../activemodel/lib"
+end
+
 $:.unshift(File.dirname(__FILE__) + '/../lib')
-$:.unshift(File.dirname(__FILE__) + '/../../activesupport/lib')
-$:.unshift(File.dirname(__FILE__) + '/../../activemodel/lib')
 
 $:.unshift(File.dirname(__FILE__) + '/lib')
 $:.unshift(File.dirname(__FILE__) + '/fixtures/helpers')
 $:.unshift(File.dirname(__FILE__) + '/fixtures/alternate_helpers')
 
-bundler = File.join(File.dirname(__FILE__), '..', 'vendor', 'gems', 'environment')
-require bundler if File.exist?("#{bundler}.rb")
-
 begin
   %w( rack rack/test sqlite3 ).each { |lib| require lib }
 rescue LoadError => e