namebench: don't depend on :python.

Use the system Python instead.

Formula/namebench.rb

@@ -5,16 +5,16 @@ class Namebench < Formula
   url 'https://namebench.googlecode.com/files/namebench-1.3.1-source.tgz'
   sha1 '2e6ca5a4f20512cb967c5ac43b023cc38c271131'
 
-  depends_on :python
-
   option 'no-third-party', 'Do not install bundled third-party modules'
 
   def install
+    ENV["PYTHONPATH"] = lib+"python2.7/site-packages"
     ENV['NO_THIRD_PARTY']='1' if build.include?('no-third-party')
 
     system "python", "setup.py", "install", "--prefix=#{prefix}",
                                             "--install-data=#{lib}/python2.7/site-packages"
 
-    bin.install bin/'namebench.py' => 'namebench'
+    bin.install "namebench.py" => "namebench"
+    bin.env_script_all_files(libexec+'bin', :PYTHONPATH => ENV['PYTHONPATH'])
   end
 end