lookaside: We now use sha512 to upload the sources
Of course, downloads continue using the hash declared in the 'sources'
file.
But when we start uploading with sha512, these 'sources' file will start
containing sha512 hashes, and so these downloads will start using sha512
as well.
https://fedorahosted.org/rel-eng/ticket/5846
Signed-off-by: Mathieu Bridon <bochecha@daitauha.fr>