RooAbsReal: fix plotting bug (invisible curves), avoid overflowing the evaluation error list
RooAbsReal: fix plotting bug (invisible curves), avoid overflowing the evaluation error list

patch on behalf of our LHCb P2VV friends (G. Raven et al.)

tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot