parted bug/enhancement

So imagine, you want to edit the root partition of your server (to enlarge it), and you suddenly could not do that anymore with your favourite tool parted. Today I was confronted with this error on a SUSE Linux Enterprise Server 12 (SLES12SP5) machine using parted 3.1 : Error: Partition /dev/sda2 is being used. You must unmount it before you modify it with Parted. What fresh hell is this? Maybe it is an “enhancement”?