repos: Include repo filename in the failed to load error string
repos: Include repo filename in the failed to load error string

https://bugzilla.redhat.com/show_bug.cgi?id=1136837

rpm-software-management/libhif,juhp/libhif,rpm-software-management/libdnf,Conan-Kudo/libhif,rpm-software-management/libdnf,Conan-Kudo/libhif,Conan-Kudo/libhif,edynox/libdnf,rpm-software-management/libhif,cgwalters/libhif,edynox/libdnf,edynox/libdnf,edynox/libdnf,hughsie/libhif,cgwalters/libhif,hughsie/libhif,rpm-software-management/libdnf,juhp/libhif,cgwalters/libhif,rpm-software-management/libdnf,rpm-software-management/libhif,hughsie/libhif,Conan-Kudo/libhif,hughsie/libhif,rpm-software-management/libhif,cgwalters/libhif