Description of problem:
I'm trying to install Fedora 21 using kickstart which worked three weeks ago, on 2014-09-24.

The only storage-related thing which was changed in the kickstart from 2014-09-24 that:
"volgroup vg_root pv.01"
was replaced with
"volgroup vg_root pv.01 --pesize=4096"

Version-Release number of selected component:
anaconda-21.48.8-1

The following was filed automatically by anaconda:
anaconda 21.48.8-1 exception report
Traceback (most recent call first):
  File "/usr/lib/python2.7/site-packages/blivet/deviceaction.py", line 617, in __init__
    raise ValueError("this device's formatting cannot be modified")
  File "/usr/lib/python2.7/site-packages/blivet/__init__.py", line 892, in initializeDisk
    destroy_action = ActionDestroyFormat(disk)
  File "/usr/lib/python2.7/site-packages/blivet/__init__.py", line 856, in clearPartitions
    self.initializeDisk(disk)
  File "/usr/lib64/python2.7/site-packages/pyanaconda/kickstart.py", line 595, in execute
    storage.clearPartitions()
  File "/usr/lib64/python2.7/site-packages/pyanaconda/kickstart.py", line 1929, in doKickstartStorage
    ksdata.clearpart.execute(storage, ksdata, instClass)
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/tui/spokes/storage.py", line 372, in execute
    doKickstartStorage(self.storage, self.data, self.instclass)
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/tui/hubs/summary.py", line 53, in setup
    spoke.execute()
  File "/usr/lib64/python2.7/site-packages/pyanaconda/ui/tui/__init__.py", line 170, in setup
    should_schedule = obj.setup(self.ENVIRONMENT)
  File "/sbin/anaconda", line 1362, in <module>
    anaconda._intf.setup(ksdata)
ValueError: this device's formatting cannot be modified

Additional info:
addons:         com_redhat_kdump
cmdline:        /usr/bin/python  /sbin/anaconda
cmdline_file:   inst.sshd dhcpclass=ipa-lab-vms ks=http://gordo.idm.lab.bos.redhat.com/cblr/svc/op/ks/profile/Fedora-21-x86_64-developer-brq
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         3.17.0-301.fc21.x86_64
product:        Fedora"
release:        Cannot get release name.
type:           anaconda
version:        Fedora

Potential duplicate: bug 1150043