def get_revision():
git_bin = smoke_zephyr.utilities.which('<STR_LIT>')<EOL>if not git_bin:<EOL><INDENT>return None<EOL><DEDENT>proc_h = subprocess.Popen(<EOL>(git_bin, '<STR_LIT>', '<STR_LIT>'),<EOL>stdout=subprocess.PIPE,<EOL>stderr=subprocess.PIPE,<EOL>close_fds=True,<EOL>cwd=os.path.dirname(os.path.abspath(__file__))<EOL>)<EOL>rev = proc_h.stdout.read().strip()<EOL>proc_h.wait()<EOL>if not len(rev):<EOL><INDENT>return None<EOL><DEDENT>return rev.decode('<STR_LIT:utf-8>')<EOL>
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