Ensure the wcs extension tests also works with system libraries.
Ensure the wcs extension tests also works with system libraries.

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