ebryn/ember-model — pull request #226 by oskarols (2013-08-26 22:17:20+00:00)
Title: Incorrect isDirty when setting belongsTo to null, or changing back to original value

Extended existing tests and added an additional one.

Since the belongsTo computed property entirely skips dirty checking if the value is falsy, setting it to null will not make the parent model dirty.

Additionally, when changing the relationship to some unsaved model, and then changing back to the original (saved) value, the model will still be dirty.