message: In the CMake build system allow MFEM_MPIEXEC and MPIEXEC_NUMPROC_FLAG
  to contain spaces, e.g. to allow -DMFEM_MPIEXEC="flux mini run".
diff: @@ -204,10 +204,10 @@ if (MFEM_USE_MPI)
  find_package(MPI REQUIRED)
  set(MPI_CXX_INCLUDE_DIRS ${MPI_CXX_INCLUDE_PATH})
  if (MFEM_MPIEXEC)
  - set(MPIEXEC ${MFEM_MPIEXEC})
  + string(REPLACE " " ";" MPIEXEC ${MFEM_MPIEXEC})
  endif()
  if (MFEM_MPIEXEC_NP)
  - set(MPIEXEC_NUMPROC_FLAG ${MFEM_MPIEXEC_NP})
  + string(REPLACE " " ";" MPIEXEC_NUMPROC_FLAG ${MFEM_MPIEXEC_NP})
  endif()
  # Parallel MFEM depends on hypre
  find_package(HYPRE REQUIRED)
  