[Array Annnotations] Fixed bug caused by merge
[Array Annnotations] Fixed bug caused by merge

A few lines of code were not changed correctly, causing empty array
annotations to fail. This is fixed now.

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