fix BookTest#test_s_load_default in Mac OS X
fix BookTest#test_s_load_default in Mac OS X

kdmsnr/review,kmuto/review,masawada/review,murashitas/review,orangain/review,orangain/review,takahashim/review,suzuki/review,krororo/review,kmuto/review,takahashim/review,kuad9/review_study,krororo/review,masawada/review,suzuki/review,murashitas/review,kmuto/review,krororo/review,kuad9/review_study