update debuginfo baseurl to account for updates (with pungi4)
    
    Similar to rhbz#1374388, debuginfo baseurl also needs update.
    As before, this affects fedora.repo but not fedora-updates.repo.
    fedora-rawhide.repo was already fixed in commit 09ed3c6.
    
    $ curl 'https://mirrors.fedoraproject.org/metalink?repo=fedora-debug-24&arch=x86_64'
    ...
    <url protocol="http" type="http" location="GB" preference="100" >http://www.mirrorservice.org/sites/dl.fedoraproject.org/pub/fedora/linux/releases/24/Everything/x86_64/debug/tree/repodata/repomd.xml</url>
    
    Signed-off-by: Alan Jenkins <alan.christopher.jenkins@gmail.com>