TST: read_csv silently drops empty row
While going over some tests, I noticed the following [here](https://github.com/pandas-dev/pandas/blob/1f6ddc4592728c1a09fc0a81ca2a00c685b60a8e/pandas/tests/io/parser/header.py#L136-L150):

```python
        df = DataFrame([[1, 2, 3, 4, 5, 6], [7, 8, 9, 10, 11, 12]],
                       index=['one', 'two'],
                       columns=MultiIndex.from_tuples(
                           [('a', 'q'), ('a', 'r'), ('a', 's'),
                            ('b', 't'), ('c', 'u'), ('c', 'v')]))


        # to_csv
        data = """,a,a,a,b,c,c
,q,r,s,t,u,v
,,,,,,
one,1,2,3,4,5,6
two,7,8,9,10,11,12"""


        result = self.read_csv(StringIO(data), header=[0, 1], index_col=0)
        tm.assert_frame_equal(df, result)
```

Is this really expected behaviour, that `pandas.read_csv` should silently discard an empty row following the header if multiple rows are passed as headers?