For reference extension builds, update book_path to reference the appropriate file location. am: 8dbd7b96cf am: ce46b86219 am: 1d2dbfe4f5
am: 6598f78068

* commit '6598f78068106179d31b0a8ccdddeb602ad12942':
  For reference extension builds, update book_path to reference the appropriate file location.

Change-Id: I2c0401d746e776a542ca02b97d927836dfeb0e98