Description of problem:
1. Reclaim disk and remove all previous partitions
2. select btrfs and review layout
3. remove root partition by clicking on the [ - ] button

Wild exception appears

Version-Release number of selected component:
anaconda-20.18-1

The following was filed automatically by anaconda:
anaconda 20.18-1 exception report
Traceback (most recent call first):
  File "/usr/lib/python2.7/site-packages/blivet/__init__.py", line 1948, in copy
    root.swaps = [new.devicetree.getDeviceByID(d.id) for d in root.swaps]
  File "/usr/lib/python2.7/site-packages/blivet/devicefactory.py", line 767, in _save_devicetree
    _blivet_copy = self.storage.copy()
  File "/usr/lib/python2.7/site-packages/blivet/devicefactory.py", line 704, in configure
    self._save_devicetree()
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/gui/spokes/custom.py", line 2112, in _destroy_device
    factory.configure()
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/gui/spokes/custom.py", line 2171, in on_remove_clicked
    self._destroy_device(device)
AttributeError: 'NoneType' object has no attribute 'id'

Additional info:
cmdline:        /usr/bin/python  /sbin/anaconda
cmdline_file:   initrd=/distrotrees/64272/initrd method=http://download-01.eng.brq.redhat.com/pub/fedora/linux/development-snapshot-20130924/20/x86_64/os/ repo=http://download-01.eng.brq.redhat.com/pub/fedora/linux/development-snapshot-20130924/20/x86_64/os/  BOOT_IMAGE=/distrotrees/64272/kernel 
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         3.11.1-300.fc20.x86_64
product:        Fedora
release:        Cannot get release name.
type:           anaconda
version:        20