head command returns exit code 0 even on 404

If I run 

``` bash
aws head MY_BUCKET/some_object_that_doesnt_exist
```

I get

``` bash
404 Not Found
```

(to stderr) however, if I then run

``` bash
echo $?
```

I get 

``` bash
0
```

Just as I do when perform aws head on an object that does exist.
