Test against io-console development branch

Use the Windows console API branch before raising the released
`io-console` dependency.

Author: nobu

Gemfile

@@ -19,4 +19,4 @@ gem 'test-unit-ruby-core'
 gem 'readline'
 
 # Only used in windows
-gem 'io-console'
+gem "io-console", github: "ruby/io-console", branch: "windows-console-support"

Rakefile

@@ -2,6 +2,14 @@ require 'bundler/gem_tasks'
 require 'rake/testtask'
 require 'rdoc/task'
 
+if io_console = Gem.loaded_specs["io-console"]
+  paths = io_console.full_require_paths
+  ENV["RUBYLIB"] = [*paths, ENV["RUBYLIB"]].compact.join(File::PATH_SEPARATOR)
+  ENV["RUBYOPT"] = ENV["RUBYOPT"].to_s.split.reject do |option|
+    /\A-r.*bundler[\\\/]setup\z/ =~ option
+  end.join(" ")
+end
+
 ENCODING_LIST = {
   test_shift_jis: Encoding::Shift_JIS,
   test_euc_jp: Encoding::EUC_JP,