CMake Warning \(author\) at .*/Modules/ExternalProject\.cmake:[0-9]+ \(message\):
  Policy CMP0225 is not set: ExternalProject sets CMAKE_INSTALL_PREFIX to
  <INSTALL_DIR> in the default configure command\.  Run "cmake --help-policy
  CMP0225" for policy details\.  Use the cmake_policy command to set the
  policy and suppress this warning\.

  ExternalProject_Add\(Sub\) uses the default configure command without a
  CMAKE_INSTALL_PREFIX\.  The OLD behavior leaves the external project's
  install prefix at the CMake default; the NEW behavior sets it to
  <INSTALL_DIR>\.
