Ruby irb Windowsのエラー対処法

ほとんど　http://royontechnology.blogspot.com/2011_02_01_archive.html
を訳しただけですが。

Windowsでirbをしようとして以下のようなエラーが出た場合には

C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:2095:in `expand_path': non-absolute home (ArgumentError)
       from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:2095:in `_rl_read_init_file'
       from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:2078:in `rl_read_init_file'
       from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:2499:in `readline_initialize_everything'
       from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:3730:in `rl_initialize'
       from C:/Ruby192/lib/ruby/site_ruby/1.9.1/rbreadline.rb:4737:in `readline'
       from C:/Ruby192/lib/ruby/site_ruby/1.9.1/readline.rb:40:in `readline'
       from C:/Ruby192/lib/ruby/1.9.1/irb/input-method.rb:115:in `gets'
       from C:/Ruby192/lib/ruby/1.9.1/irb.rb:139:in `block (2 levels) in eval_input'
       from C:/Ruby192/lib/ruby/1.9.1/irb.rb:273:in `signal_status'
       from C:/Ruby192/lib/ruby/1.9.1/irb.rb:138:in `block in eval_input'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `call'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:188:in `buf_input'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:103:in `getc'
       from C:/Ruby192/lib/ruby/1.9.1/irb/slex.rb:205:in `match_io'
       from C:/Ruby192/lib/ruby/1.9.1/irb/slex.rb:75:in `match'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:286:in `token'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:262:in `lex'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:233:in `block (2 levels) in each_top_level_statement'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `loop'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:229:in `block in each_top_level_statement'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `catch'
       from C:/Ruby192/lib/ruby/1.9.1/irb/ruby-lex.rb:228:in `each_top_level_statement'
       from C:/Ruby192/lib/ruby/1.9.1/irb.rb:155:in `eval_input'
       from C:/Ruby192/lib/ruby/1.9.1/irb.rb:70:in `block in start'
       from C:/Ruby192/lib/ruby/1.9.1/irb.rb:69:in `catch'
       from C:/Ruby192/lib/ruby/1.9.1/irb.rb:69:in `start'
       from C:/Ruby192/bin/irb:12:in `'



システム環境変数の以下の変数を削除すればとりあえず解決します。）
HOME
HOMEDRIVE
HOMEPATH
HOMESHARE

CygwinのHOMEの設定がどうやら絡んでいるらしいです。
Cygwinの不具合はまだみてません（汗