Fixing fetch bug in icon-nwp recipe.

spack_repo/packages/icon-nwp/package.py

@@ -84,7 +84,7 @@ class IconNwp(Package):
                 password = token
                 url = "{}://{}:{}@{}/{}".format(parsed.scheme, user, password, parsed.netloc, parsed.path)
 
-        self.fetcher[0].url = self.git = url
+        self.fetcher.url = self.git = url
 
         super(IconNwp, self).do_fetch(mirror_only)