The actual change is in src/mongo/shell/collection.js with the remaining changes
to adjust tests to the new api.
The "ideal" arguments are now an array of pipeline ops and an optional object
with extra top-level options for the command (such as {explain: true}. For
backwards compatibility, we still support the varargs style where each argument
is a pipeline stage, but there is no way to specify extra parameters in this
mode.
Changes:
* Nullish values in math expressions (but not accumulators) result in NULL.
* $divide or $mod by 0 now uasserts.
* uassert in math expressions if inputs are neither nullish nor numeric.
* $group fills missing accumulators with NULL rather than Undefined.
Related Tickets:
SERVER-7932 Fix handling of nullish Values in math expressions
SERVER-6144 $divide by 0 makes field disappear
