Preserve symlinks when writing .config.old files
Preserve symlinks when writing .config.old files

if .config is a symlink, then the intention is probably to overwrite the
target, but rename()ing the symlink to .config.old interferes with that.

Use the shutil.copyfile() fallback instead if .config is a symlink.

ulfalizer/Kconfiglib,ulfalizer/Kconfiglib