code: def get_revision():
  	
  	git_bin = smoke_zephyr.utilities.which('git')
  	if not git_bin:
  		return None
  	proc_h = subprocess.Popen(
  		(git_bin, 'rev-parse', 'HEAD'),
  		stdout=subprocess.PIPE,
  		stderr=subprocess.PIPE,
  		close_fds=True,
  		cwd=os.path.dirname(os.path.abspath(__file__))
  	)
  	rev = proc_h.stdout.read().strip()
  	proc_h.wait()
  	if not len(rev):
  		return None
  	return rev.decode('utf-8')
docs: Retrieve the current git revision identifier. If the git binary can not be
  	found or the repository information is unavailable, None will be returned.
  
  	:return: The git revision tag if it's available.
  	:rtype: str