Description of problem:

Migemo crashed when to input 'aiueo' on no euc-jp locale.


Version-Release number of selected component (if applicable):

0.40-15.fc17

Steps to Reproduce:
1. Run migemo as follows

  $ export LANG=ja_JP.utf-8
  $ $ echo 'aiueo' | migemo -d /usr/share/migemo/migemo-dict

Actual results:

Migemo crashed with following error:

/usr/share/ruby/vendor_ruby/migemo-dict.rb:42:in `split': invalid byte sequence in UTF-8 (ArgumentError)
        from /usr/share/ruby/vendor_ruby/migemo-dict.rb:42:in `decompose'
        from /usr/share/ruby/vendor_ruby/migemo-dict.rb:72:in `block in lookup'
        from /usr/share/ruby/vendor_ruby/bsearch.rb:53:in `bsearch_lower_boundary'
        from /usr/share/ruby/vendor_ruby/bsearch.rb:115:in `bsearch_range'
        from /usr/share/ruby/vendor_ruby/migemo-dict.rb:71:in `lookup'
        from /usr/share/ruby/vendor_ruby/migemo.rb:163:in `expand_words'
        from /usr/share/ruby/vendor_ruby/migemo.rb:180:in `block in lookup0'
        from /usr/share/ruby/vendor_ruby/migemo.rb:177:in `each'
        from /usr/share/ruby/vendor_ruby/migemo.rb:177:in `lookup0'
        from /usr/share/ruby/vendor_ruby/migemo.rb:213:in `lookup'
        from /usr/share/ruby/vendor_ruby/migemo.rb:228:in `regex'
        from /usr/bin/migemo:138:in `block in main'
        from /usr/bin/migemo:147:in `call'
        from /usr/bin/migemo:147:in `main'
        from /usr/bin/migemo:163:in `<main>'


Expected results:

show pattern of 'aiueo' with euc-jp encoding.