Thank you for taking the time to report this bug and helping to make Ubuntu better.
It isn't clear to me from the manpage that you linked that the behaviour is documented to do what you expect. Has this been reported upstream? It isn't a good idea to change behaviour on Ubuntu from all the other distributions that run sgdisk, so ideally this would be fixed upstream first so the intent is clear.
If upstream have committed a fix, then we can look into whether it is a bugfix that should be applied to existing stable Ubuntu releases, or if it is not suitable and should go into the Ubuntu development release only.
If upstream have not committed a fix, then I'm not sure it's a good idea for Ubuntu to diverge on this behaviour.
Thank you for taking the time to report this bug and helping to make Ubuntu better.
It isn't clear to me from the manpage that you linked that the behaviour is documented to do what you expect. Has this been reported upstream? It isn't a good idea to change behaviour on Ubuntu from all the other distributions that run sgdisk, so ideally this would be fixed upstream first so the intent is clear.
If upstream have committed a fix, then we can look into whether it is a bugfix that should be applied to existing stable Ubuntu releases, or if it is not suitable and should go into the Ubuntu development release only.
If upstream have not committed a fix, then I'm not sure it's a good idea for Ubuntu to diverge on this behaviour.