It's possible to do a warm reboot into a new kernel without ever powering down and re-initializing RAM.
Also, it may not even be fully rebooting, but instead doing something like killing all processes except init (launchd) which then starts up the installer. I haven't run it, so I don't know exactly what it's doing, but there are several ways to "reboot" without fully rebooting.
Also, it may not even be fully rebooting, but instead doing something like killing all processes except init (launchd) which then starts up the installer. I haven't run it, so I don't know exactly what it's doing, but there are several ways to "reboot" without fully rebooting.