fixes#8641
In the example, setting SYSTEMD_WANTS instead of appending may prevent
other autostart services attached by earlier udev rules from launching.
This commit changes = to += to fix this behavior.
fixes#8639
The priority of 40 for the udev rules as stated in to documentation
applies the rule too early on some systems, which prevents the rule from
matching. This commit changes the priority to 80.
borg1 needed this due to its transactional / rollback behaviour:
if there was uncommitted stuff in the repo, next repo opening automatically
rolled back to last commit. thus we needed checkpoint archives to reference
chunks and commit the repo.
borg2 does not do that anymore, unused chunks are only removed when the
user invokes borg compact.
thus, if a borg create gets interrupted, the user can just run borg create
again and it will find some chunks are already in the repo, making progress
even if borg create gets frequently interrupted.
