emberjs/data — pull request #876 by tricknotes (2013-04-11 16:53:26+00:00)
Title: Fix belongsTo relationships to models with id 0

I fixed the following failing test:
```
Module Failed: DS.belongsTo
Test Failed: belongsTo supports relationships to models with id 0
Assertion Failed: the tag property should return a tag
Expected: true, Actual: false
Assertion Failed: the tag shuld have name
Expected: friendly, Actual: null
Assertion Failed: relationship object is the same as object retrieved directly
Expected: , Actual: null
```