Why does building ParMETIS with CMake as an external project give me this error?

Question

I want to use ExternalProject_Add from CMake to build ParMETIS, but during the build process there is an error.

I have had success building other libraries with this feature without too many issues. I have tried CMake version 3.10.2, 3.10.3 and 3.11.1 all giving the same error.

cmake_minimum_required(VERSION 3.10.2)

include(ExternalProject)
set(LIB_EXT ${CMAKE_CURRENT_SOURCE_DIR}/../external)
set(BUILD_EXT ${LIB_EXT}/builds)

set(PARMETIS_ROOT ${BUILD_EXT}/parmetis)
ExternalProject_Add(external_parmetis
  URL http://glaros.dtc.umn.edu/gkhome/fetch/sw/parmetis/parmetis-4.0.3.tar.gz
  URL_HASH SHA256=f2d9a231b7cf97f1fee6e8c9663113ebf6c240d407d3c118c55b3633d6be6e5f
  PREFIX ${PARMETIS_ROOT}
  SOURCE_DIR ${LIB_EXT}/parmetis-4.0.3
  BUILD_IN_SOURCE ON
  DOWNLOAD_DIR ${LIB_EXT}
  CONFIGURE_COMMAND make config
  BUILD_COMMAND make
  INSTALL_COMMAND ""
  )

The configure step works, but after all of the targets are built I get an error. I don't think this "s" target is a real target.

[100%] Built target pometis
make[5]: *** No rule to make target `s'.  Stop.
make[4]: *** [all] Error 2