fetch: rename 'tarball' to 'download'

Library/Homebrew/cmd/fetch.rb

 require 'formula'
 
-# Downloads the tarballs for the given formulae to the Cache
-
 module Homebrew extend self
   def fetch
     raise FormulaUnspecifiedError if ARGV.named.empty?
@@ -27,15 +25,15 @@ module Homebrew extend self
 
   def fetch_formula f
     f.cached_download.rmtree if already_fetched?(f) && ARGV.force?
-    tarball, _ = f.fetch
+    download, _ = f.fetch
 
     # FIXME why are strategies returning different types?
-    return unless tarball.is_a? Pathname
+    return unless download.is_a? Pathname
 
-    puts "Downloaded to: #{tarball}" unless already_fetched?(f)
-    puts Checksum::TYPES.map { |t| "#{t.to_s.upcase}: #{tarball.send(t)}" }
+    puts "Downloaded to: #{download}" unless already_fetched?(f)
+    puts Checksum::TYPES.map { |t| "#{t.to_s.upcase}: #{download.send(t)}" }
 
-    f.verify_download_integrity(tarball)
+    f.verify_download_integrity(download)
   rescue ChecksumMismatchError => e
     Homebrew.failed = true
     opoo "Formula reports different #{e.hash_type}: #{e.expected}"