allow special header overrides
allow special header overrides

pllim/astropy,StuartLittlefair/astropy,aleksandr-bakanov/astropy,stargaser/astropy,astropy/astropy,astropy/astropy,lpsinger/astropy,larrybradley/astropy,saimn/astropy,MSeifert04/astropy,mhvk/astropy,mhvk/astropy,dhomeier/astropy,mhvk/astropy,stargaser/astropy,saimn/astropy,larrybradley/astropy,StuartLittlefair/astropy,aleksandr-bakanov/astropy,pllim/astropy,aleksandr-bakanov/astropy,stargaser/astropy,lpsinger/astropy,saimn/astropy,pllim/astropy,MSeifert04/astropy,saimn/astropy,astropy/astropy,dhomeier/astropy,stargaser/astropy,pllim/astropy,saimn/astropy,mhvk/astropy,lpsinger/astropy,aleksandr-bakanov/astropy,larrybradley/astropy,dhomeier/astropy,StuartLittlefair/astropy,dhomeier/astropy,astropy/astropy,larrybradley/astropy,dhomeier/astropy,StuartLittlefair/astropy,pllim/astropy,astropy/astropy,StuartLittlefair/astropy,larrybradley/astropy,lpsinger/astropy,MSeifert04/astropy,mhvk/astropy,lpsinger/astropy,MSeifert04/astropy