code: def get_scm():
    
    # TODO(John Sirois): Extract a module/class to carry the bootstrap logic.
    global _SCM
    if not _SCM:
      from pants.scm.git import Git
      # We know about git, so attempt an auto-configure
      worktree = Git.detect_worktree()
      if worktree and os.path.isdir(worktree):
        git = Git(worktree=worktree)
        try:
          logger.debug('Detected git repository at {} on branch {}'.format(worktree, git.branch_name))
          set_scm(git)
        except git.LocalException as e:
          logger.info('Failed to load git repository at {}: {}'.format(worktree, e))
    return _SCM
docs: Returns the pants Scm if any.
  
    :API: public