Hi,

I noticed for packages not specifying any URL the CRAN importer emits home-page
URLs like https://cran.r-project.org/web/packages/<package> (without trailing
slash). These are permanent redirects, thus the linter complains about them.
One option would be adding a trailing slash or use the canonical URL, as
provided by CRAN (on the bottom of the description page). The attached patch
does the latter.

Lars