Right now our weekly Debian versioning scheme is VERSION="$BASE_VERSION~git$DATE.$SHA-$CLEAN_COMPONENT".
This sorts weekly releases AFTER the BASE_VERSION, so when both stable
and unstable are enabled, we never get weekly versions installed.
https://wiki.debian.org/Versioning proposes {upcoming_version}~git{date}.{hash}-{revision} for nightly releases, which means we would have to know the release number of the upcoming version in advance. I don't think that is useful for us.
By switching from a tilde to a dash, our weekly versions are not sorted
above the stable base version and we will install the weekly versions
over the base version, which I believe is closer to what we intend.
Fixes: #2081