unpack: use correct constant scope for DATA

Formula::DATA only worked by accident of implementation; DATA during the
build is actually Object::DATA, so we should mirror that here.

This reverts commit b12444ba6e1ac1d596a70ff4c777d9386d0791ac.

Library/Contributions/cmd/brew-unpack.rb

@@ -28,22 +28,13 @@ module UnpackPatch
     return unless ARGV.flag? "--patch"
 
     begin
-      # Silence complaints about re-setting constants.
       old_verbose = $VERBOSE
       $VERBOSE = nil
-      Formula.const_set "DATA", ScriptDataReader.load(path)
+      Object.const_set "DATA", ScriptDataReader.load(path)
     ensure
       $VERBOSE = old_verbose
     end
 
-    # Legacy patches are fixed by setting Formula::DATA.
-    # Now, handle instances of IOPatch.
-    patchlist.select{|p| p.is_a? IOPatch}.each do |patch|
-      if patch.instance_variable_get(:@io) == :DATA
-        patch.instance_variable_set :@io, ScriptDataReader.load(path)
-      end
-    end
-
     super
   end
 end