Comment 19 for bug 1615381

@jarnos, this is a separate issue fixed later, calculating upgradable packages leaves the upgradable packages in the cache, and u-u counts them as the reverse dependencies of the first kernel to be removed.
This keeps the first kernel on the system, but when there are no upgradable packages in a later run this kernel can be removed, too.

See:
https://github.com/mvo5/unattended-upgrades/commit/93d43fbcd53c5df5ce69a16b26a981bf06ce3085
https://github.com/mvo5/unattended-upgrades/commit/654898b05c933047ca8c97df655743aab0898db1
https://github.com/mvo5/unattended-upgrades/commit/1a39eb257ad786902de11add212879241919be44