Same results with 4.2.rc6-1.1.g4a2cf4a

medina:~ # eject /dev/sdb

systemd-journalctl log:

Aug 13 10:45:10 medina.novell.com udisksd[1953]: Cleaning up mount point /run/media/luis/LUIS (device 8:17 is not mounted)
Aug 13 10:45:10 medina.novell.com ntfs-3g[3278]: Unmounting /dev/sdb1 (LUIS)
Aug 13 10:45:10 medina.novell.com udisksd[1953]: Cleaning up mount point /run/media/luis/ALBERTO (device 8:18 is not mounted)

medina:~ # udisksctl power-off -b /dev/sdb

systemd-journalctl log:

Aug 13 10:45:21 medina.novell.com bluetoothd[997]: Endpoint unregistered: sender=:1.28 path=/MediaEndpoint/A2DPSource
Aug 13 10:45:21 medina.novell.com bluetoothd[997]: Endpoint unregistered: sender=:1.28 path=/MediaEndpoint/A2DPSink
Aug 13 10:45:21 medina.novell.com systemd[1321]: pam_unix(systemd-user:session): session closed for user gdm
Aug 13 10:45:22 medina.novell.com udisksd[1953]: Powering off /dev/sdb - successfully sent SCSI command START STOP UNIT
Aug 13 10:45:22 medina.novell.com kernel: sd 6:0:0:0: [sdb] Synchronizing SCSI cache
Aug 13 10:45:23 medina.novell.com kernel: sd 6:0:0:0: [sdb] Synchronize Cache(10) failed: Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
Aug 13 10:45:23 medina.novell.com udisksd[1953]: Powered off /dev/sdb - successfully wrote to sysfs path /sys/devices/pci0000:00/0000:00:14.0/usb3/3-1/remove
Aug 13 10:45:23 medina.novell.com kernel: usb 3-1: USB disconnect, device number 4
Aug 13 10:45:23 medina.novell.com kernel: usb 3-1: new SuperSpeed USB device number 5 using xhci_hcd
Aug 13 10:45:23 medina.novell.com kernel: usb 3-1: New USB device found, idVendor=0bc2, idProduct=2321
Aug 13 10:45:23 medina.novell.com kernel: usb 3-1: New USB device strings: Mfr=2, Product=3, SerialNumber=1
Aug 13 10:45:23 medina.novell.com kernel: usb 3-1: Product: Expansion
Aug 13 10:45:23 medina.novell.com kernel: usb 3-1: Manufacturer: Seagate
Aug 13 10:45:23 medina.novell.com kernel: usb 3-1: SerialNumber: NA4BQHLX
Aug 13 10:45:23 medina.novell.com kernel: scsi host7: uas
Aug 13 10:45:23 medina.novell.com kernel: scsi 7:0:0:0: Direct-Access     Seagate  Expansion        0502 PQ: 0 ANSI: 6
Aug 13 10:45:23 medina.novell.com kernel: sd 7:0:0:0: Attached scsi generic sg1 type 0
Aug 13 10:45:23 medina.novell.com kernel: sd 7:0:0:0: [sdb] 3907029167 512-byte logical blocks: (2.00 TB/1.81 TiB)
Aug 13 10:45:23 medina.novell.com kernel: sd 7:0:0:0: [sdb] 4096-byte physical blocks
Aug 13 10:45:23 medina.novell.com kernel: sd 7:0:0:0: [sdb] Write Protect is off
Aug 13 10:45:23 medina.novell.com kernel: sd 7:0:0:0: [sdb] Mode Sense: 4f 00 00 00
Aug 13 10:45:23 medina.novell.com kernel: sd 7:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
Aug 13 10:45:23 medina.novell.com mtp-probe[3392]: checking bus 3, device 5: "/sys/devices/pci0000:00/0000:00:14.0/usb3/3-1"
Aug 13 10:45:23 medina.novell.com mtp-probe[3392]: bus: 3, device: 5 was not an MTP device
Aug 13 10:45:25 medina.novell.com kernel:  sdb: sdb1 sdb2 sdb3
Aug 13 10:45:25 medina.novell.com kernel: sd 7:0:0:0: [sdb] Attached SCSI disk
Aug 13 10:45:25 medina.novell.com kernel: iwlwifi 0000:03:00.0: request for firmware file 'iwlwifi-7265D-11.ucode' failed.
Aug 13 10:45:25 medina.novell.com kernel: iwlwifi 0000:03:00.0: Direct firmware load for iwlwifi-7265D-10.ucode failed with error -2
Aug 13 10:45:25 medina.novell.com kernel: iwlwifi 0000:03:00.0: Falling back to user helper
Aug 13 10:45:25 medina.novell.com kernel: hfsplus: write access to a journaled filesystem is not supported, use the force option at your own risk, mounting read-only.
Aug 13 10:45:25 medina.novell.com ntfs-3g[3421]: Version 2014.2.15 external FUSE 29
Aug 13 10:45:25 medina.novell.com ntfs-3g[3421]: Mounted /dev/sdb1 (Read-Write, label "LUIS", NTFS 3.1)
Aug 13 10:45:25 medina.novell.com ntfs-3g[3421]: Cmdline options: rw,nodev,nosuid,uid=1000,gid=100,dmask=0077,fmask=0177,uhelper=udisks2
Aug 13 10:45:25 medina.novell.com ntfs-3g[3421]: Mount options: rw,nodev,nosuid,uhelper=udisks2,allow_other,nonempty,relatime,default_permissions,fsname=/dev/sdb1,blkdev,blksize=4096
Aug 13 10:45:25 medina.novell.com ntfs-3g[3421]: Global ownership and permissions enforced, configuration type 1
Aug 13 10:45:25 medina.novell.com udisksd[1953]: Mounted /dev/sdb2 at /run/media/luis/ALBERTO on behalf of uid 1000
Aug 13 10:45:25 medina.novell.com udisksd[1953]: Mounted /dev/sdb1 at /run/media/luis/LUIS on behalf of uid 1000
Aug 13 10:45:25 medina.novell.com org.gtk.Private.UDisks2VolumeMonitor[2161]: disc.c:332: error opening file BDMV/index.bdmv
Aug 13 10:45:25 medina.novell.com org.gtk.Private.UDisks2VolumeMonitor[2161]: disc.c:332: error opening file BDMV/BACKUP/index.bdmv
Aug 13 10:45:25 medina.novell.com org.gtk.Private.UDisks2VolumeMonitor[2161]: disc.c:332: error opening file BDMV/index.bdmv
Aug 13 10:45:25 medina.novell.com org.gtk.Private.UDisks2VolumeMonitor[2161]: disc.c:332: error opening file BDMV/BACKUP/index.bdmv

P.S.

medina:~ # uname -a
Linux medina.novell.com 4.2.0-rc6-1.g4a2cf4a-default #1 SMP Mon Aug 10 01:50:31 UTC 2015 (4a2cf4a) x86_64 x86_64 x86_64 GNU/Linux