tests: add guard check for suid support This adds a check for setuid and setgid support and guards a part of a test requiring this particular filesystem feature. Such feature is notably missing in the Nix/NixOS build sandbox and was causing the whole test to fail for the mercurial package. Differential Revision: https://phab.mercurial-scm.org/D11739

import os


def killme(ui, repo, hooktype, **wkargs):
    os._exit(80)