I met bug when my csv header began with comma

[zyxbest]

situation

When I upload a file like this,the first header is '' since the line begins with comma.(See the up left empty cell)

Then DataPusher raise error as The data was invalid (for example: a numeric value is out of range or was inserted into a text field).

debug

The directly reason of the error is headers_dicts in DataPusher:
I log the headers_dicts then it shows:

[
    {
        'type': u'numeric',
        'id': u'name'
    },
    {
        'type': u'text',
        'id': u'total'
    },
    {
        'type': u'numeric',
        'id': u'male_share'
    },
    {
        'type': u'numeric',
        'id': u'female_share'
    },
    {
        'type': u'numeric',
        'id': u'gap'
    }
]

Obviously there is some shifting thing cuz the name should be text and the total should be numeric

I read the code :
1. offset, headers = messytables.headers_guess(row_set.sample)
2. types = messytables.type_guess(row_set.sample, types=TYPES, strict=False)
The first empty header would be stored as u'',It's totally fine.
Here len(types)==len(headers)
3. headers = [header.strip() for header in headers if header.strip()]
Then this line dropped the u'',but didn't drop correspond type, that is ,len(types)== len(headers) -1

4. `headers_dicts = [dict(id=field[0], type=TYPE_MAPPING[str(field[1])]) for field in zip(headers, types)]`

Finally in this line we get a wrong headers_dicts, zipfunc would not raise error even if parameters have different length.