fails(Matching MRI 1.8.7 bug):Bignum#<=> returns 1 when self is Infinity and other is a Bignum
fails(Matching MRI 1.8.7 bug):Bignum#<=> returns 1 when self is negative and other is -Infinity
fails(Matching MRI 1.8.7 bug):Bignum#<=> returns -1 when self is -Infinity and other is negative
