Revert "Generate the bottle download URL correctly."

This reverts commit 092004e7820791030f568af0e3b03389ea4f7ee3.

Library/Homebrew/formula.rb

@@ -61,8 +61,6 @@ class Formula
     CHECKSUM_TYPES.each { |type| set_instance_variable type }
 
     @downloader = download_strategy.new @spec_to_use.url, name, version, @spec_to_use.specs
-
-    @bottle_url ||= bottle_base_url + bottle_filename(self) if @bottle_sha1
   end
 
   # if the dir is there, but it's empty we consider it not installed
@@ -634,6 +632,7 @@ private
 
       bottle_block.instance_eval &block
       @bottle_version, @bottle_url, @bottle_sha1 = bottle_block.data
+      @bottle_url ||= bottle_base_url + bottle_filename(self) if @bottle_sha1
     end
 
     def mirror val, specs=nil