I'm having the same issue reported here, but the solutions aren't really related to the extra lines, they're pointing out that the original file is being opened incorrectly.
Python 3.3 CSV.Writer writes extra blank rows
I have the same issue writing out a list, the following code
sample_data = [[1,2],[3,4],[5,6]]
with open('text.csv', 'w') as csvfile:
writer = csv.writer(csvfile, dialect=csv.excel)
writer.writerows(sample_data)
produces
1,2
3,4
5,6
Whilst changing the dialect to dialect=csv.unix_dialect (which as far as I can see only changes from lineterminator = '\r\n' to lineterminator = '\n'
produces the correct result
1,2
3,4
5,6
Am I doing something wrong, quite likely given I've just migrated to Py3.3