fix for python 2.6
fix for python 2.6

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