Ah, thanks for spotting this. Only the `ModelMixin` `setValue` invokes `setIfExists` , and is overridden by the `XM.Model` `setValue` which does not. So I will delete the incorrect version (this one) and then we will only have one implementation of this function, which is the true solution.

ModelMixin version:
https://github.com/xtuple/xtuple/blob/master/lib/backbone-x/source/model_mixin.js#L1077

Model version (notice incorrect comment re: meta):
https://github.com/xtuple/xtuple/blob/master/lib/backbone-x/source/model.js#L936