Add regression test for get_config
Add regression test for get_config

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