Description of problem:
When doing something like

nova flavor-create ... --swap 256 --ephemeral 1 ...
glance image-create ...
nova boot ... --swap 256 --ephemeral size=1 ... test

then the disk.info on the compute node running the instance contains entries for disk, disk.eph0, and disk.swap, these images all are present on the compute node disk and everything is as expected.

But after

nova stop test
nova start test

the disk.info contains entries for disk, disk.eph0, disk.local, disk.swap but there is no disk.local present thus the instance fails to boot. If manually copying disk.eph0 as disk.local then the instance boots up and will use disk.local instead of disk.eph0 from there on as the ephemeral disk.

See also https://bugs.launchpad.net/nova/+bug/1305423.