makerにSJISのファイルを食わせるとわかりにくいエラーになる

[kmuto]

review-webmaker  config.yml
Traceback (most recent call last):
	21: from /home/kmuto/review/bin/review-webmaker:15:in `<main>'
	20: from /home/kmuto/review/lib/review/webmaker.rb:47:in `execute'
	19: from /home/kmuto/review/lib/review/webmaker.rb:99:in `execute'
	18: from /home/kmuto/review/lib/review/webmaker.rb:116:in `generate_html_files'
	17: from /home/kmuto/review/lib/review/webmaker.rb:247:in `copy_frontmatter'
	16: from /home/kmuto/review/lib/review/webmaker.rb:262:in `build_indexpage'
	15: from /home/kmuto/review/lib/review/webmaker.rb:262:in `open'
	14: from /home/kmuto/review/lib/review/webmaker.rb:275:in `block in build_indexpage'
	13: from /home/kmuto/review/lib/review/webtocprinter.rb:9:in `book_to_string'
	12: from /home/kmuto/review/lib/review/webtocprinter.rb:16:in `print_book'
	11: from /home/kmuto/review/lib/review/tocprinter.rb:86:in `build_result_array'
	10: from /home/kmuto/review/lib/review/book/base.rb:98:in `parts'
	 9: from /home/kmuto/review/lib/review/book/base.rb:304:in `read_parts'
	 8: from /home/kmuto/review/lib/review/book/base.rb:289:in `postscripts'
	 7: from /home/kmuto/review/lib/review/book/part.rb:29:in `mkpart_from_namelist'
	 6: from /home/kmuto/review/lib/review/book/part.rb:29:in `map'
	 5: from /home/kmuto/review/lib/review/book/part.rb:29:in `block in mkpart_from_namelist'
	 4: from /home/kmuto/review/lib/review/book/chapter.rb:32:in `mkchap_ifexist'
	 3: from /home/kmuto/review/lib/review/book/chapter.rb:32:in `new'
	 2: from /home/kmuto/review/lib/review/book/chapter.rb:54:in `initialize'
	 1: from /home/kmuto/review/lib/review/book/chapter.rb:73:in `find_first_header_option'
/home/kmuto/review/lib/review/book/chapter.rb:73:in `===': invalid byte sequence in UTF-8 (ArgumentError)
rake aborted!
Command failed with status (1): [review-webmaker  config.yml...]
lib/tasks/review.rake:117:in `block in <top (required)>'
Tasks: TOP => web => webroot
(See full trace by running task with --trace)

invalid byte sequenceから推測は立つので拾ってまともなエラーにしたい。 review-vol, review-indexも同じところでエラーになっている。