Switch back to monkey-patching

Also gsub! some particular formula contents to work around older
formulae ("brewkit" isn't around anymore, and url is expected to
be a method, not an instance variable).

Library/Homebrew/dev-cmd/extract.rb

@@ -15,20 +15,19 @@ require "utils/git"
 require "formulary"
 require "tap"
 
-module ExtractExtensions
+class BottleSpecification
-  refine BottleSpecification do
   def method_missing(m, *_args, &_block)
     # no-op
   end
-  end
+end
 
-  refine Module do
+class Module
   def method_missing(m, *_args, &_block)
     # no-op
   end
-  end
+end
 
-  refine DependencyCollector do
+class DependencyCollector
   def parse_symbol_spec(spec, tags)
     case spec
     when :x11        then X11Requirement.new(spec.to_s, tags)
@@ -45,15 +44,17 @@ module ExtractExtensions
     end
   end
 
+  module Compat
     def parse_string_spec(spec, tags)
       opoo "'depends_on ... => :run' is disabled. There is no replacement." if tags.include?(:run) && ARGV.debug?
       super
     end
   end
+
+  prepend Compat
 end
 
 module Homebrew
-  using ExtractExtensions
   module_function
 
   def extract
@@ -124,6 +125,8 @@ module Homebrew
   def formula_at_revision(repo, name, file, rev)
     return if rev.empty?
     contents = Git.last_revision_of_file(repo, file, before_commit: rev)
+    contents.gsub!("@url=", "url ")
+    contents.gsub!("require 'brewkit'", "require 'formula'")
     Formulary.from_contents(name, file, contents)
   end
 end