Remove compat/download_strategy.

Library/Homebrew/compat.rb

@@ -1,7 +1,6 @@
 require "compat/os/mac"
 require "compat/dependable"
 require "compat/dependency_collector"
-require "compat/download_strategy"
 require "compat/fileutils"
 require "compat/formula_support"
 require "compat/hbc"

Library/Homebrew/compat/download_strategy.rb

@@ -1,16 +0,0 @@
-class AbstractFileDownloadStrategy
-  # TODO: This can be removed after a month because downloads
-  #       will be outdated anyways at that point.
-  module Compat
-    def initialize(url, name, version, **meta)
-      super
-
-      old_cached_location = @cache/"#{name}-#{version}#{ext}"
-
-      return unless old_cached_location.exist?
-      FileUtils.mv old_cached_location, cached_location, force: true
-    end
-  end
-
-  prepend Compat
-end