off by one error in sexp_bignum_mul need an extra digit to fit carries
off by one error in sexp_bignum_mul
need an extra digit to fit carries

norton/chibi-scheme,norton/chibi-scheme,norton/chibi-scheme,holmescn/chibi-scheme,norton/chibi-scheme,holmescn/chibi-scheme,norton/chibi-scheme,holmescn/chibi-scheme,holmescn/chibi-scheme,holmescn/chibi-scheme,norton/chibi-scheme