REGR: 1.3 behavior change with groupby and asindex=False
#### Code Sample, a copy-pastable example

```python
pd.DataFrame(columns=["date", "crew_member_id"])
    .groupby(["date", "crew_member_id"], as_index=False)
    .sum()
```

#### Problem description

With 1.3rc1 this fails with `ValueError: Length of values (0) does not match length of index (1)` while 1.2 returns and empty frame.

#### Expected Output

If this is the expected behavior fine. Just wanted to ensure that it is not an accidental regression.
