Test "is_extension" after a round trip to dict (#18188)
Test "is_extension" after a round trip to dict (#18188)

closes #3887
closes #3853
iulian787/spack,LLNL/spack,iulian787/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack,iulian787/spack,LLNL/spack,LLNL/spack