Fix mistake that was accidentally working in Python 2.x but not 3.x
Fix mistake that was accidentally working in Python 2.x but not 3.x

tbabej/astropy,mhvk/astropy,AustereCuriosity/astropy,dhomeier/astropy,mhvk/astropy,pllim/astropy,DougBurke/astropy,larrybradley/astropy,joergdietrich/astropy,DougBurke/astropy,dhomeier/astropy,MSeifert04/astropy,dhomeier/astropy,AustereCuriosity/astropy,StuartLittlefair/astropy,StuartLittlefair/astropy,lpsinger/astropy,tbabej/astropy,kelle/astropy,aleksandr-bakanov/astropy,kelle/astropy,funbaker/astropy,bsipocz/astropy,joergdietrich/astropy,lpsinger/astropy,AustereCuriosity/astropy,bsipocz/astropy,kelle/astropy,saimn/astropy,dhomeier/astropy,mhvk/astropy,joergdietrich/astropy,stargaser/astropy,joergdietrich/astropy,stargaser/astropy,saimn/astropy,lpsinger/astropy,tbabej/astropy,lpsinger/astropy,bsipocz/astropy,tbabej/astropy,bsipocz/astropy,astropy/astropy,larrybradley/astropy,MSeifert04/astropy,DougBurke/astropy,lpsinger/astropy,pllim/astropy,saimn/astropy,stargaser/astropy,dhomeier/astropy,saimn/astropy,pllim/astropy,stargaser/astropy,aleksandr-bakanov/astropy,MSeifert04/astropy,astropy/astropy,tbabej/astropy,larrybradley/astropy,StuartLittlefair/astropy,MSeifert04/astropy,kelle/astropy,astropy/astropy,aleksandr-bakanov/astropy,AustereCuriosity/astropy,StuartLittlefair/astropy,saimn/astropy,mhvk/astropy,funbaker/astropy,joergdietrich/astropy,kelle/astropy,larrybradley/astropy,AustereCuriosity/astropy,mhvk/astropy,funbaker/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,astropy/astropy,funbaker/astropy,pllim/astropy,pllim/astropy,larrybradley/astropy,DougBurke/astropy,astropy/astropy