am 16401ad4: Revert "sparse_img.py: Don\'t write empty map groups."
am 16401ad4: Revert "sparse_img.py: Don\'t write empty map groups."

* commit '16401ad4256178fbe7a2cd8588e6dbf9a6c63180':
  Revert "sparse_img.py: Don't write empty map groups."

xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build,xorware/android_build