New release 7.3.1 created a default get value error

Hi,
from version 7.3.0 to 7.3.1 the behaviour of get changed.

if Box is instanciated with:

```
b = Box({'foo': {'bar': 1}})
```

doing 

```
b.get('foo.grab.plum', 4)
```
should return 4 even if grab is not a key of foo. 

This behaviour worked fine in 7.3.0 but not anymore in 7.3.1 ... seems related to the recent change in #275 