Publisher dies if natbib complains error.
Publisher dies if natbib complains error.

This may be too strict. But it is never bad to be too strict.

This should give an error on #192 (instead of giving question marks)

katyhuff/scipy_proceedings,michaelpacer/scipy_proceedings,katyhuff/scipy_proceedings,katyhuff/scipy_proceedings,michaelpacer/scipy_proceedings,michaelpacer/scipy_proceedings,sbenthall/scipy_proceedings,sbenthall/scipy_proceedings,sbenthall/scipy_proceedings