class Bundler::RubygemsIntegration

def replace_bin_path(specs)
  gem_class = (class << Gem ; self ; end)
  redefine_method(gem_class, :bin_path) do |name, *args|
    exec_name = args.first
    if exec_name == 'bundle'
      return ENV['BUNDLE_BIN_PATH']
    end
    spec = nil
    if exec_name
      spec = specs.find { |s| s.executables.include?(exec_name) }
      spec or raise Gem::Exception, "can't find executable #{exec_name}"
    else
      spec = specs.find  { |s| s.name == name }
      exec_name = spec.default_executable or raise Gem::Exception, "no default executable for #{spec.full_name}"
    end
    gem_bin = File.join(spec.full_gem_path, spec.bindir, exec_name)
    gem_from_path_bin = File.join(File.dirname(spec.loaded_from), spec.bindir, exec_name)
    File.exist?(gem_bin) ? gem_bin : gem_from_path_bin
  end
end