Comment 16 for bug 1626070

Hi Richud,
while the bug here was a special case with the wily type being used in Xenial and therefore to be retained until the EOL of xenial has passed.
It is different for other machine types like the ones you see issues with atm.

Keeping the old types "almost forever" is a common habit as people just don't think about them usually. That has for several users caused much more pain later on. Therefore it is intended to (please choose your preferred word) hint/encourage/enforce users to finally upgrade machine types to pick up new features, stability and security fixes bound to new types only.

See https://wiki.ubuntu.com/QemuKVMMigration#Support_Matrix

Due to that the qemu in Ubuntu 18.10 dropped Zesty and Yakkety intentionally.