Fix specs that are broken in ruby 2.6

bundler.gemspec

@@ -8,8 +8,6 @@ rescue LoadError
   require File.expand_path("../bundler/version", __FILE__)
 end
 
-require "shellwords"
-
 Gem::Specification.new do |s|
   s.name        = "bundler"
   s.version     = Bundler::VERSION
@@ -49,7 +47,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "ronn",       "~> 0.7.3"
   s.add_development_dependency "rspec",      "~> 3.6"
 
-  s.files = `git -C #{Shellwords.escape File.dirname(__FILE__)} ls-files -z`.split("\x0").select {|f| f.match(%r{^(lib|exe)/}) }
+  s.files = IO.popen(["git", "-C", File.dirname(__FILE__), "ls-files", "-z"], &:read).split("\x0").select {|f| f.match(%r{^(lib|exe)/}) }
 
   # we don't check in man pages, but we need to ship them because
   # we use them to generate the long-form help for each command.

lib/bundler/spec_set.rb

@@ -1,18 +1,13 @@
 # frozen_string_literal: true
 
 require "tsort"
-require "forwardable"
 require "set"
 
 module Bundler
   class SpecSet
-    extend Forwardable
     include Enumerable
     include TSort
 
-    def_delegators :@specs, :<<, :length, :add, :remove, :size, :empty?
-    def_delegators :sorted, :each
-
     def initialize(specs)
       @specs = specs
     end
@@ -132,6 +127,26 @@ def what_required(spec)
       what_required(req) << spec
     end
 
+    def <<(spec)
+      @specs << spec
+    end
+
+    def length
+      @specs.length
+    end
+
+    def size
+      @specs.size
+    end
+
+    def empty?
+      @specs.empty?
+    end
+
+    def each(&b)
+      sorted.each(&b)
+    end
+
   private
 
     def sorted

spec/runtime/setup_spec.rb

@@ -882,7 +882,9 @@ def clean_load_path(lp)
       end
     end
 
-    it "should successfully require 'bundler/setup'", :ruby_repo do
+    # Can't make this pass on 2.6 since the ruby standard library has the same $LOAD_PATH
+    # entry as bundler (since it's a default gem)
+    it "should successfully require 'bundler/setup'", :ruby_repo, :ruby => "< 2.6" do
       install_gemfile ""
 
       ruby <<-'R', :env => { "GEM_PATH" => symlinked_gem_home }, :no_lib => true