apt: Drop repo for unstable
apt: Drop repo for unstable

It tends to fail during updates with the HTTP
  redirector from Debian, and we don't use it
  anyways, so it doesn't seem worth keeping.

hashbang/shell-etc,KellerFuchs/shell-etc,KellerFuchs/shell-etc,hashbang/shell-etc,hashbang/shell-etc,hashbang/shell-etc,hashbang/shell-etc,hashbang/shell-etc,KellerFuchs/shell-etc,KellerFuchs/shell-etc,KellerFuchs/shell-etc,hashbang/shell-etc,hashbang/shell-etc,KellerFuchs/shell-etc