The same record different instances save() behavior
This is correct, calling a model's save method will wholesale update the row in the database with the field data present on the model instance **at the time of saving**.  item2 will not automatically receive changes made to item1, since they are separate instances.  This is intended behavior.

If you want to only update a single column, use `update`:

``` python

ItemModel.update(other_field=item2.other_field).where(id=item2.id).execute()
```

**Please considering a bug:**
I'm in situation which fetching the same db record but different instance, each modified somewhere.

``` python
    item1 = get_item(filter='A') # return new instance of rec A
    item2 = get_item(filter='A') # also return new instance of rec A

    # item1 and item2 refer to the same db record, but different instance

    item1.some_field = 'some value'
    item1.save()

    item2.other_field = 'other value'
    item2.save()
```

The **item1** data won't saved correctly after committing transaction (different field changes)
