If we build a GPT image for flashing on arbitrary disks, chances are there is space left after
that second partition-table, placed at end of image.
When launching parted interactively, we get asked "Not all of the space available to ... appears to be used" and asked "Fix/Ignore?".
The code does not look like the job done on "fix" is available from any other mean, whether lib or parted command. And the exception system does not look like it will work with no tty attached, so
just using "echo fix | parted /dev/whatever print" will just not workaround this.