stage.steal_source: preserve symlinks
stage.steal_source: preserve symlinks

 This avoids dangling symlink errors. ignore_dangling_symlinks option would be more-targeted but is only available for Python >= 3.2 (#28318)
LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack,LLNL/spack