add a warning when IPAC metadata writing fails
add a warning when IPAC metadata writing fails

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