Warn about there being more than one max score, rather than raising an error
Warn about there being more than one max score, rather than raising an error

jhamrick/nbgrader,ellisonbg/nbgrader,jhamrick/nbgrader,ellisonbg/nbgrader,alope107/nbgrader,jupyter/nbgrader,dementrock/nbgrader,EdwardJKim/nbgrader,jupyter/nbgrader,alope107/nbgrader,jupyter/nbgrader,EdwardJKim/nbgrader,jupyter/nbgrader,modulexcite/nbgrader,jdfreder/nbgrader,jupyter/nbgrader,ellisonbg/nbgrader,modulexcite/nbgrader,jdfreder/nbgrader,ellisonbg/nbgrader,jhamrick/nbgrader,EdwardJKim/nbgrader,EdwardJKim/nbgrader,dementrock/nbgrader,MatKallada/nbgrader,jhamrick/nbgrader,MatKallada/nbgrader