Description of problem:
latest boot.iso when select ext USB HD /dev/sdb  "cannot remove non-leaf device"

Version-Release number of selected component:
anaconda-21.26-1

The following was filed automatically by anaconda:
anaconda 21.26-1 exception report
Traceback (most recent call first):
  File "/usr/lib/python2.7/site-packages/blivet/devicetree.py", line 346, in _removeDevice
    raise ValueError("Cannot remove non-leaf device '%s'" % dev.name)
  File "/usr/lib/python2.7/site-packages/blivet/devicetree.py", line 1921, in hide
    self._removeDevice(device, moddisk=False)
  File "/usr/lib/python2.7/site-packages/blivet/devicetree.py", line 1909, in hide
    self.hide(d)
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/gui/spokes/storage.py", line 730, in on_back_clicked
    self.storage.devicetree.hide(disk)
ValueError: Cannot remove non-leaf device 'sda4'

Additional info:
cmdline:        /usr/bin/python  /sbin/anaconda
cmdline_file:   initrd=initrd.img inst.stage2=hd:LABEL=Fedora\x20rawhide\x20x86_64 quiet BOOT_IMAGE=vmlinuz 
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         3.14.0-0.rc5.git2.1.fc21.x86_64
product:        Fedora
release:        Cannot get release name.
type:           anaconda
version:        rawhide