def enable_revprop_changes(repo_dir):
"""Enable revprop changes in a repository REPOS_DIR by creating a
pre-revprop-change hook script and (if appropriate) making it executable."""
hook_path = main.get_pre_revprop_change_hook_path(repo_dir)
main.create_python_hook_script(hook_path, 'import sys; sys.exit(0)')
