I dug into Nova client source code, and what it does is a detailed listing/search to get the right resource and tries to guess if the <instance-id> is an id or an human name (because it also works with the display_name of an instance).
I dug into Nova client source code, and what it does is a detailed listing/search to get the right resource and tries to guess if the <instance-id> is an id or an human name (because it also works with the display_name of an instance).