Comment # 6 on bug 1154973 from Jonathan Kang

It's mainly about when to set and reset upgradeMode.

Running "pkcon update" leads to calling get-updates and update-packages. A list
of update candidates will be passed from get-updates to update-packages.

* If upgradeMode is set in get-updates and reset to FALSE when it's done,
update-packages won't be able to perform a dup-like action in Tumbleweed.
* If upgradeMode is set in get-updates and not reset when finished, removing/
installing packages will lead to a full dup-style system upgrade in Tumbleweed.
* We can try to set upgradeMode in update-packages, but update-packages is
responsible for updating specific packages and upgrading the whole system. But
the way PackageKit works make it difficult to differentiate between those two.