With udev 220, there is no change event any more for block devices when programs like mkfs or e2label open and change them. This causes e. g. udisks2 to break.

Simple reproducer:

 # modprobe scsi_debug
 # udevadm monitor

Then run this in another terminal: `# sh -c '> /dev/sdb'

(Replace sdb with the actual scsi_debug drive. This ought to be a harmless command, but don't take chances in destroying your hard disk!)

Up to udev 219 you get

KERNEL[40.913525] change /devices/pseudo_0/adapter0/host2/target2:0:0/2:0:0:0/block/sdb (block)
UDEV [41.021205] change /devices/pseudo_0/adapter0/host2/target2:0:0/2:0:0:0/block/sdb (block)

With 220 there is no uevent.