Update fetch command for generalized bottle implementation

Library/Homebrew/cmd/fetch.rb

@@ -17,12 +17,24 @@ module Homebrew extend self
 
     puts "Fetching: #{bucket * ', '}" if bucket.size > 1
     bucket.each do |f|
+      if fetch_bottle?(f)
+        fetch_formula(f.bottle)
+      else
         fetch_formula(f)
         f.resources.each do |r|
           fetch_resource(r)
         end
       end
     end
+  end
+
+  def fetch_bottle? f
+    return true if ARGV.force_bottle? && f.bottle
+    return false unless f.bottle && f.pour_bottle?
+    return false if ARGV.build_from_source? || ARGV.build_bottle?
+    return false unless f.bottle.compatible_cellar?
+    return true
+  end
 
   def fetch_resource r
     puts "Resource: #{r.name}"