#9316

This is a failing test that illustrates the problem.

[4/6] TestBigMath#test_division = 0.00 s     
  1) Failure:
TestBigMath#test_division [test/bigdecimal/test_bigmath.rb:18]:
Expected |1486.868686869 - 1487.0| (0.13131313100006992) to be <= 0.001.
#9316

Reverting to the 2.0.0 implementation of BigDecimal makes this problem go away.