[server] Initialize Repository without a tasks manager in ServerMigrationHelper.restore_database() We don't need a tasks manager here I think. Thus instantiate the Repository from its class directly instead of using config.repository() which set a tasks manager.

version=3
opts=uversionmangle=s/(rc|a|b|c)/~$1/ \
https://pypi.debian.net/cubicweb/cubicweb-(.+)\.(?:zip|tgz|tbz|txz|(?:tar\.(?:gz|bz2|xz)))