Added test to check download_file error type (issue pointed out by @kbarbary)
Added test to check download_file error type (issue pointed out by @kbarbary)

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