[NixIO] Fix for t_stop being before end time in test
[NixIO] Fix for t_stop being before end time in test

rgerkin/python-neo,theunissenlab/python-neo,mgr0dzicki/python-neo,INM-6/python-neo,apdavison/python-neo,JuliaSprenger/python-neo,samuelgarcia/python-neo,NeuralEnsemble/python-neo