downloader: Resume only files that were originaly downloaded by Librepo (RhBug: 1130685)
downloader: Resume only files that were originaly downloaded by Librepo (RhBug: 1130685)

Use extended attributes for this.

For each file that we are going to download add an extended attribute
"user.Librepo.DownloadInProgress".
When the download is finished successfully, remove the attribute.
If the librepo is terminated during download, then the attribute is still present
and in the next run, the librepo can continue.
If user tries to download a file that already exists in the local dir
and checksum doesn't match (the file is probably not downloaded completly)
but the file doesn't contain the attribute, then the download won't be
resumed.

bgamari/librepo,Tojaj/librepo,rholy/librepo,Conan-Kudo/librepo,Tojaj/librepo,cgwalters/librepo,rholy/librepo,rholy/librepo,Conan-Kudo/librepo,rpm-software-management/librepo,cgwalters/librepo,rholy/librepo,bgamari/librepo,rpm-software-management/librepo,cgwalters/librepo,Conan-Kudo/librepo,Tojaj/librepo,bgamari/librepo,rpm-software-management/librepo,cgwalters/librepo