This constructos may create an object with incorrect scale:
==== Here is the minimized test ====
class java_lang_Bignum_constructor_1 {
  public static void main(String args[]) {
    System.out.println(new java.lang.Bignum("5e2",5)); //should print 500.00000
    System.out.println(new java.lang.Bignum("test",5)); //should print 0.00000
  }
}
==== Here is the output of the test ====
500
0