It seems with python 2 it returns an error rather than following the redirect. This change checks the return code and if it is a redirect it sets the URL to check to Location
Coverage decreased (-0.09%) to 38.188% when pulling 9570e889449de5a76f534b3acfd3ce9e63101b8f on iiif-3.0 into 4a7edafa9520c9d0c2f71dbcb5e6e1eb975039c2 on master.
It seems with python 2 it returns an error rather than following the redirect. This change checks the return code and if it is a redirect it sets the URL to check to Location