"""

        return self._get_all_revisions()

    @classmethod

    def _run_git_command(cls, cmd, cwd=None):

        """

        Runs given ``cmd`` as git command and returns output bytes in a tuple

        (stdout, stderr) ... or raise RepositoryError.

        :param cmd: git command to be executed

        :param cwd: passed directly to subprocess

        """

        # need to clean fix GIT_DIR !

        gitenv = dict(os.environ)

        gitenv.pop('GIT_DIR', None)

        gitenv['GIT_CONFIG_NOGLOBAL'] = '1'

        assert isinstance(cmd, list), cmd

        cmd = [settings.GIT_EXECUTABLE_PATH, '-c', 'core.quotepath=false'] + cmd

        try:

            p = subprocessio.SubprocessIOChunker(cmd, cwd=cwd, env=gitenv, shell=False)

        except (EnvironmentError, OSError) as err:

            # output from the failing process is in str(EnvironmentError)

            msg = ("Couldn't run git command %s.\n"

                   "Subprocess failed with '%s': %s\n" %

                   (cmd, type(err).__name__, err)

            ).strip()

            log.error(msg)

            raise RepositoryError(msg)

        try:

            stdout = b''.join(p.output)

            stderr = b''.join(p.error)

        finally:

            p.close()

        # TODO: introduce option to make commands fail if they have any stderr output?

        if stderr:

            log.debug('stderr from %s:\n%s', cmd, stderr)

        else:

            log.debug('stderr from %s: None', cmd)

        return stdout, stderr

    def run_git_command(self, cmd):

        """

        Runs given ``cmd`` as git command with cwd set to current repo.

        Returns stdout as unicode str ... or raise RepositoryError.

        """

        cwd = None

        if os.path.isdir(self.path):

            cwd = self.path

        stdout, _stderr = self._run_git_command(cmd, cwd=cwd)

        return safe_str(stdout)

    @classmethod

    def _check_url(cls, url):

        """

        Function will check given url and try to verify if it's a valid

        link. Sometimes it may happened that git will issue basic

        auth request that can cause whole API to hang when used from python

        or other external calls.

        On failures it'll raise urllib2.HTTPError, exception is also thrown

        when the return code is non 200

        """

        # check first if it's not an local url

        if os.path.isdir(url) or url.startswith('file:'):

            return True

        if url.startswith('git://'):

            return True

        if '+' in url[:url.find('://')]:

            url = url[url.find('+') + 1:]

        handlers = []

        url_obj = mercurial.util.url(safe_bytes(url))

        test_uri, authinfo = url_obj.authinfo()

        if not test_uri.endswith(b'info/refs'):

            test_uri = test_uri.rstrip(b'/') + b'/info/refs'

        url_obj.passwd = b'*****'

        cleaned_uri = str(url_obj)

        if authinfo:

            # create a password manager

            passmgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()

            passmgr.add_password(*authinfo)

            handlers.extend((mercurial.url.httpbasicauthhandler(passmgr),

                             mercurial.url.httpdigestauthhandler(passmgr)))

        o = urllib.request.build_opener(*handlers)

        o.addheaders = [('User-Agent', 'git/1.7.8.0')]  # fake some git

        req = urllib.request.Request(

            "%s?%s" % (

                urllib.parse.urlencode({"service": 'git-upload-pack'})

            ))

        try:

            resp = o.open(req)

            if resp.code != 200:

                raise Exception('Return Code is not 200')

        except Exception as e:

            # means it cannot be cloned

            raise urllib.error.URLError("[%s] org_exc: %s" % (cleaned_uri, e))

        # now detect if it's proper git repo

        gitdata = resp.read()

        if b'service=git-upload-pack' not in gitdata:

            raise urllib.error.URLError(

                "url [%s] does not look like an git" % cleaned_uri)

        return True

    def _get_repo(self, create, src_url=None, update_after_clone=False,

                  bare=False):

        if create and os.path.exists(self.path):

            raise RepositoryError("Location already exist")

        if src_url and not create:

            raise RepositoryError("Create should be set to True if src_url is "

                                  "given (clone operation creates repository)")

        try:

            if create and src_url:

                GitRepository._check_url(src_url)

                self.clone(src_url, update_after_clone, bare)

                return Repo(self.path)

            elif create:

                os.makedirs(self.path)

                if bare:

                    return Repo.init_bare(self.path)

                else:

                    return Repo.init(self.path)

            else:

                return Repo(self.path)

        except (NotGitRepository, OSError) as err:

            raise RepositoryError(err)

    def _get_all_revisions(self):

        # we must check if this repo is not empty, since later command

        # fails if it is. And it's cheaper to ask than throw the subprocess

        # errors

        try:

            self._repo.head()

        except KeyError:

            return []

        rev_filter = settings.GIT_REV_FILTER

        cmd = ['rev-list', rev_filter, '--reverse', '--date-order']

        try:

            so = self.run_git_command(cmd)

        except RepositoryError:

            # Can be raised for empty repositories

            return []

        return so.splitlines()

    def _get_all_revisions2(self):

        # alternate implementation using dulwich

        includes = [ascii_str(sha) for key, (sha, type_) in self._parsed_refs.items()

                    if type_ != b'T']

        return [c.commit.id for c in self._repo.get_walker(include=includes)]

    def _get_revision(self, revision):

        """

        Given any revision identifier, returns a 40 char string with revision hash.

        """

        if self._empty:

            raise EmptyRepositoryError("There are no changesets yet")

        if revision in (None, '', 'tip', 'HEAD', 'head', -1):

            revision = -1

        if isinstance(revision, int):

            try:

                return self.revisions[revision]

            except IndexError:

                msg = "Revision %r does not exist for %s" % (revision, self.name)

                raise ChangesetDoesNotExistError(msg)

        if isinstance(revision, str):

            if revision.isdigit() and (len(revision) < 12 or len(revision) == revision.count('0')):

                try:

                    return self.revisions[int(revision)]

                except IndexError:

                    msg = "Revision %r does not exist for %s" % (revision, self)

                    raise ChangesetDoesNotExistError(msg)

            # get by branch/tag name

            _ref_revision = self._parsed_refs.get(safe_bytes(revision))

            if _ref_revision:  # and _ref_revision[1] in [b'H', b'RH', b'T']:

                return ascii_str(_ref_revision[0])