Specifying logical volume size as a percent of free space in the volume group in a RHEL 6 kickstart

Issue

• Need to kickstart hosts with a disk layout containing LVM volume groups that leave some spare space for LVM snapshots.
• The following partitioning layout was proposed which seemed unambitious and reasonable:

# disk partitions:
part /boot --fstype=ext4 --size=256
part pv.001 --size=1 --grow
# volume group:
volgroup vg_root pv.001
# logical volumes:
logvol swap --name=lv_swap --vgname=vg_root --size=2048
# let the root volume fill 90% of the volume group, we'll leave 10% available for a snapshot
logvol  /  --fstype=ext4 --vgname=vg_root --name=lv_root --percent=90

• anaconda throws an error Unable to create new logical volume with no extents. And the traceback is as follows when --percent was used to logvol statement

anaconda 13.21.82 exception report
  Traceback (most recent call first):
    File "/usr/lib/anaconda/storage/partitioning.py", line 1727, in growLVM
       grow = portion * vg.vgFree
    File "/usr/lib/anaconda/storage/partitioning.py", line 233, in doAutoPartition
       growLVM(anaconda.id.storage)
    File "/usr/lib/anaconda/dispatch.py", line 208, in moveStep
       rc = stepFunc(self.anaconda)
    File "/usr/lib/anaconda/dispatch.py", line 126, in gotoNext
       self.moveStep()
    File "/usr/lib/anaconda/dispatch.py", line 231, in currentStep
       self.gotoNext()
    File "/usr/lib/anaconda/gui.py", line 1371, in setScreen
       (step, anaconda) = self.anaconda.dispatch.currentStep()
    File "/usr/lib/anaconda/gui.py", line 1550, in setup_window
       self.setScreen()
    File "/usr/lib/anaconda/gui.py", line 1563, in run
       self.setup_window(runres)
    File "/usr/lib/anaconda/gui.py", line 1288, in run
       self.icw.run (self.runres)
    File "/usr/bin/anaconda", line 1115, in <module>
       anaconda.intf.run(anaconda)
AttributeError: 'LVMVolumeGroupDevice' object has no attribute 'vgFree'