Fix a bug when generating the error message in `generate_config_file`.  The stdout and stderr parts are rightly decoded as UTF-8, but then they are formatted into a byte string which (at least on my platform) treats the UTF-8 as ascii and boom! exception is raised trying to generate the error message.
Fix a bug when generating the error message in `generate_config_file`.  The stdout and stderr parts are rightly decoded as UTF-8, but then they are formatted into a byte string which (at least on my platform) treats the UTF-8 as ascii and boom! exception is raised trying to generate the error message.

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