RHEL 6 kickstarts with multiple clearpart lines fail with a traceback and a KeyError

Issue

• RHEL 6.2 kickstarts will fail with a KeyError on the first disk if the kickstart file contains multiple clearpart lines.

  clearpart --drives=/dev/vda --all
  clearpart --drives=/dev/vdb --all
  

• Anaconda traceback and error:

  anaconda 13.21.149 exception report
  Traceback (most recent call first):
    File "/usr/lib/anaconda/storage/partitioning.py", line 1033, in allocatePartitions
      disklabel = disklabels[_disk.path]
    File "/usr/lib/anaconda/storage/partitioning.py", line 906, in doPartitioning
      allocatePartitions(storage, disks, partitions, free)
    File "/usr/lib/anaconda/storage/partitioning.py", line 248, in doAutoPartition
      exclusiveDisks=anaconda.id.storage.clearPartDisks)
    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 1423, in setScreen
      (step, anaconda) = self.anaconda.dispatch.currentStep()
    File "/usr/lib/anaconda/gui.py", line 1615, in setup_window
      self.setScreen()
    File "/usr/lib/anaconda/gui.py", line 1628, in run
      self.setup_window()
    File "/usr/lib/anaconda/gui.py", line 1336, in run
      self.icw.run ()
    File "/usr/bin/anaconda", line 1116, in <module>
      anaconda.intf.run(anaconda)
  KeyError: '/dev/vda'