fixed test for wcs_from_points. now tests linear fit and sip fit individually
fixed test for wcs_from_points. now tests linear fit and sip fit individually

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