Bottom border not allowed to be None

Created originally on Bitbucket by vitkorob (Victor K)

Bottom border not allowed to be None. See line https://bitbucket.org/openpyxl/openpyxl/src/2.6/openpyxl/styles/borders.py?fileviewer=file-view-default#borders.py-79

In this code I want only the top border to be thin, and the rest as is. In 2.6.x an exception occurs.

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thin_border = Border(top=Side(style='thin'), left=None, right=None, bottom=None, diagonal=None)

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