Do not make non-existent XDG directory on start (#357)

Author: nobu

lib/irb/init.rb

@@ -379,11 +379,9 @@ def IRB.rc_file_generators
     end
     if xdg_config_home = ENV["XDG_CONFIG_HOME"]
       irb_home = File.join(xdg_config_home, "irb")
-      unless File.exist? irb_home
-        require 'fileutils'
-        FileUtils.mkdir_p irb_home
+      if File.directory?(irb_home)
+        yield proc{|rc| irb_home + "/irb#{rc}"}
       end
-      yield proc{|rc| irb_home + "/irb#{rc}"}
     end
     if home = ENV["HOME"]
       yield proc{|rc| home+"/.irb#{rc}"}

test/irb/test_init.rb

@@ -36,13 +36,16 @@ def test_setup_with_minimum_argv_does_not_change_dollar0
     def test_rc_file
       tmpdir = @tmpdir
       Dir.chdir(tmpdir) do
+        ENV["XDG_CONFIG_HOME"] = "#{tmpdir}/xdg"
         IRB.conf[:RC_NAME_GENERATOR] = nil
         assert_equal(tmpdir+"/.irb#{IRB::IRBRC_EXT}", IRB.rc_file)
         assert_equal(tmpdir+"/.irb_history", IRB.rc_file("_history"))
+        assert_file.not_exist?(tmpdir+"/xdg")
         IRB.conf[:RC_NAME_GENERATOR] = nil
         FileUtils.touch(tmpdir+"/.irb#{IRB::IRBRC_EXT}")
         assert_equal(tmpdir+"/.irb#{IRB::IRBRC_EXT}", IRB.rc_file)
         assert_equal(tmpdir+"/.irb_history", IRB.rc_file("_history"))
+        assert_file.not_exist?(tmpdir+"/xdg")
       end
     end