udev: try first re-reading the partition table

mounted partitions:
  # dd if=/dev/zero of=/dev/sda bs=1 count=1
  UDEV  [4157.369250] change   .../0:0:0:0/block/sda (block)
  UDEV  [4157.375059] change   .../0:0:0:0/block/sda/sda1 (block)
  UDEV  [4157.397088] change   .../0:0:0:0/block/sda/sda2 (block)
  UDEV  [4157.404842] change   .../0:0:0:0/block/sda/sda4 (block)

unmounted partitions:
  # dd if=/dev/zero of=/dev/sdb bs=1 count=1
  UDEV  [4163.450217] remove   .../target6:0:0/6:0:0:0/block/sdb/sdb1 (block)
  UDEV  [4163.593167] change   .../target6:0:0/6:0:0:0/block/sdb (block)
  UDEV  [4163.713982] add      .../target6:0:0/6:0:0:0/block/sdb/sdb1 (block)