pydata/pandas — pull request #5390 by jreback (2013-10-30 21:50:14+00:00)
Title: API: raise SettingWithCopy when chained assignment is detected

I think their are some more cases, but what do you think about this?

```
df = DataFrame({ 'A' : np.arange(2), 'B' : np.array(np.arange(2,4),dtype=np.float64)})

In [1]: df = DataFrame({ 'A' : np.arange(2), 'B' : np.array(np.arange(2,4),dtype=np.float64)})

In [2]: df['A'][0] = -5

In [3]: df.loc[0]['A'] = -10
SettingWithCopy: trying to set value on a copy
```