BigDecimal inconsistent between 2.0, 2.1 (probably incorrect on 2.1)
BigDecimal / BigDecimal seems to round off.
The test case has not been reduced to trivial, but it's pretty small and should be pretty clear.
passes for ruby 2.0.
Fails for ruby 2.1
ruby 2.1.0p0 (2013-12-25 revision 44422) [x86_64-darwin13.0]