Description of problem:
1. Selected the root disk in the disk setup.
2. Selected custom partitioning.
3. Selected Btrfs.
4. Selected the automatic partitioning.
5. Received an error about no disk available.

Version-Release number of selected component:
anaconda-21.37-1

The following was filed automatically by anaconda:
anaconda 21.37-1 exception report
Traceback (most recent call first):
  File "/usr/lib64/python2.7/site-packages/pyanaconda/bootloader.py", line 1356, in is_valid_stage2_device
    if self.stage2_device.type == "mdarray" and \
  File "/usr/lib/python2.7/site-packages/blivet/__init__.py", line 1661, in sanityCheck
    self.bootloader.is_valid_stage2_device(stage2)
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/gui/spokes/custom.py", line 2186, in _do_autopart
    exns = self._storage_playground.sanityCheck()
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/gui/spokes/custom.py", line 120, in decorated
    return func(*args, **kwargs)
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/gui/spokes/custom.py", line 2207, in on_create_clicked
    self._do_autopart()
AttributeError: 'NoneType' object has no attribute 'type'

Additional info:
cmdline:        /usr/bin/python  /sbin/anaconda
cmdline_file:   BOOT_IMAGE=/images/pxeboot/vmlinuz inst.stage2=hd:LABEL=Fedora\x20rawhide\x20x86_64 quiet
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         3.15.0-0.rc7.git0.1.fc21.x86_64
product:        Fedora
release:        Cannot get release name.
type:           anaconda
version:        rawhide