After MAAS deploys a node, the node *SHOULD* be set to PXE-boot. This is, in fact, what happens on most computers (or does recently; the behavior of booting from disk was a bug several months ago). In recent tests (for 16.04.5 regression testing), I've seen this misbehavior of having the disk-boot option first in the boot list only on two Lenovo computers, so it looks like there's some new interaction going on.
After MAAS deploys a node, the node *SHOULD* be set to PXE-boot. This is, in fact, what happens on most computers (or does recently; the behavior of booting from disk was a bug several months ago). In recent tests (for 16.04.5 regression testing), I've seen this misbehavior of having the disk-boot option first in the boot list only on two Lenovo computers, so it looks like there's some new interaction going on.