def _get_all_revisions2(self):

        #alternate implementation using dulwich

        includes = [x[1][0] for x in self._parsed_refs.iteritems()

                    if x[1][1] != 'T']

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

    def _get_revision(self, revision):

        """

        For git backend we always return integer here. This way we ensure

        that changset's revision attribute would become integer.

        """

        pattern = re.compile(r'^[[0-9a-fA-F]{12}|[0-9a-fA-F]{40}]$')

        is_bstr = lambda o: isinstance(o, (str, unicode))

        is_null = lambda o: len(o) == revision.count('0')

        if len(self.revisions) == 0:

            raise EmptyRepositoryError("There are no changesets yet")

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

            revision = self.revisions[-1]

        if ((is_bstr(revision) and revision.isdigit() and len(revision) < 12)

            or isinstance(revision, int) or is_null(revision)):

            try:

                revision = self.revisions[int(revision)]

            except:

                raise ChangesetDoesNotExistError("Revision %r does not exist "

                    "for this repository %s" % (revision, self))

        elif is_bstr(revision):

            # get by branch/tag name

            _ref_revision = self._parsed_refs.get(revision)

            _tags_shas = self.tags.values()

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

                return _ref_revision[0]

            # maybe it's a tag ? we don't have them in self.revisions

            elif revision in _tags_shas:

                return _tags_shas[_tags_shas.index(revision)]

            elif not pattern.match(revision) or revision not in self.revisions:

                raise ChangesetDoesNotExistError("Revision %r does not exist "

                    "for this repository %s" % (revision, self))

        # Ensure we return full id

        if not pattern.match(str(revision)):

            raise ChangesetDoesNotExistError("Given revision %r not recognized"

                % revision)

        return revision

    def _get_archives(self, archive_name='tip'):

        for i in [('zip', '.zip'), ('gz', '.tar.gz'), ('bz2', '.tar.bz2')]:

                yield {"type": i[0], "extension": i[1], "node": archive_name}

    def _get_url(self, url):

        """

        Returns normalized url. If schema is not given, would fall to

        filesystem (``file:///``) schema.

        """

        url = str(url)

        if url != 'default' and not '://' in url:

            url = ':///'.join(('file', url))

        return url

    @LazyProperty

    def name(self):

        return os.path.basename(self.path)

    @LazyProperty

    def last_change(self):

        """

        Returns last change made on this repository as datetime object

        """

        return date_fromtimestamp(self._get_mtime(), makedate()[1])

    def _get_mtime(self):

        try:

            return time.mktime(self.get_changeset().date.timetuple())

        except RepositoryError:

            idx_loc = '' if self.bare else '.git'

            # fallback to filesystem

            in_path = os.path.join(self.path, idx_loc, "index")

            he_path = os.path.join(self.path, idx_loc, "HEAD")

            if os.path.exists(in_path):

                return os.stat(in_path).st_mtime

            else:

                return os.stat(he_path).st_mtime

    @LazyProperty

    def description(self):

        idx_loc = '' if self.bare else '.git'

        undefined_description = u'unknown'

        description_path = os.path.join(self.path, idx_loc, 'description')

        if os.path.isfile(description_path):

            return safe_unicode(open(description_path).read())

        else:

            return undefined_description

    @LazyProperty

    def contact(self):

        undefined_contact = u'Unknown'

        return undefined_contact

    @property

    def branches(self):

        if not self.revisions:

            return {}

        sortkey = lambda ctx: ctx[0]

        _branches = [(x[0], x[1][0])

                     for x in self._parsed_refs.iteritems() if x[1][1] == 'H']

        return OrderedDict(sorted(_branches, key=sortkey, reverse=False))

    @LazyProperty

    def tags(self):

        return self._get_tags()

    def _get_tags(self):

        if not self.revisions:

            return {}

        sortkey = lambda ctx: ctx[0]

        _tags = [(x[0], x[1][0])

                 for x in self._parsed_refs.iteritems() if x[1][1] == 'T']

        return OrderedDict(sorted(_tags, key=sortkey, reverse=True))

    def tag(self, name, user, revision=None, message=None, date=None,

            **kwargs):

        """

        Creates and returns a tag for the given ``revision``.

        :param name: name for new tag

        :param user: full username, i.e.: "Joe Doe <joe.doe@example.com>"

        :param revision: changeset id for which new tag would be created

        :param message: message of the tag's commit

        :param date: date of tag's commit

        :raises TagAlreadyExistError: if tag with same name already exists

        """

        if name in self.tags:

            raise TagAlreadyExistError("Tag %s already exists" % name)

        changeset = self.get_changeset(revision)

        message = message or "Added tag %s for commit %s" % (name,

            changeset.raw_id)

        self._repo.refs["refs/tags/%s" % name] = changeset._commit.id

        self._parsed_refs = self._get_parsed_refs()

        self.tags = self._get_tags()

        return changeset

    def remove_tag(self, name, user, message=None, date=None):

        """

        Removes tag with the given ``name``.

        :param name: name of the tag to be removed

        :param user: full username, i.e.: "Joe Doe <joe.doe@example.com>"

        :param message: message of the tag's removal commit

        :param date: date of tag's removal commit

        :raises TagDoesNotExistError: if tag with given name does not exists

        """

        if name not in self.tags:

            raise TagDoesNotExistError("Tag %s does not exist" % name)

        tagpath = posixpath.join(self._repo.refs.path, 'refs', 'tags', name)

        try:

            os.remove(tagpath)

            self._parsed_refs = self._get_parsed_refs()

            self.tags = self._get_tags()

        except OSError, e:

            raise RepositoryError(e.strerror)

    @LazyProperty

    def _parsed_refs(self):

        return self._get_parsed_refs()

    def _get_parsed_refs(self):

        refs = self._repo.get_refs()

        keys = [('refs/heads/', 'H'),

                ('refs/remotes/origin/', 'RH'),

                ('refs/tags/', 'T')]

        _refs = {}

        for ref, sha in refs.iteritems():

            for k, type_ in keys:

                if ref.startswith(k):

                    _key = ref[len(k):]

                    if type_ == 'T':

                        obj = self._repo.get_object(sha)

                        if isinstance(obj, Tag):

                            sha = self._repo.get_object(sha).object[1]

                    _refs[_key] = [sha, type_]

                    break

        return _refs

    def _heads(self, reverse=False):

        refs = self._repo.get_refs()

        heads = {}

        for key, val in refs.items():

            for ref_key in ['refs/heads/', 'refs/remotes/origin/']:

                if key.startswith(ref_key):

                    n = key[len(ref_key):]

                    if n not in ['HEAD']:

                        heads[n] = val

        return heads if reverse else dict((y, x) for x, y in heads.iteritems())

    def get_changeset(self, revision=None):

        """

        Returns ``GitChangeset`` object representing commit from git repository

        at the given revision or head (most recent commit) if None given.

        """

        if isinstance(revision, GitChangeset):

            return revision

        revision = self._get_revision(revision)

        changeset = GitChangeset(repository=self, revision=revision)

        return changeset

    def get_changesets(self, start=None, end=None, start_date=None,

           end_date=None, branch_name=None, reverse=False):

        """

        Returns iterator of ``GitChangeset`` objects from start to end (both

        are inclusive), in ascending date order (unless ``reverse`` is set).

        :param start: changeset ID, as str; first returned changeset

        :param end: changeset ID, as str; last returned changeset

        :param start_date: if specified, changesets with commit date less than

          ``start_date`` would be filtered out from returned set

        :param end_date: if specified, changesets with commit date greater than

          ``end_date`` would be filtered out from returned set

        :param branch_name: if specified, changesets not reachable from given

          branch would be filtered out from returned set

        :param reverse: if ``True``, returned generator would be reversed

          (meaning that returned changesets would have descending date order)

        :raise BranchDoesNotExistError: If given ``branch_name`` does not

            exist.

        :raise ChangesetDoesNotExistError: If changeset for given ``start`` or

          ``end`` could not be found.

        """

        if branch_name and branch_name not in self.branches:

            raise BranchDoesNotExistError("Branch '%s' not found" \

                                          % branch_name)

        # %H at format means (full) commit hash, initial hashes are retrieved

        # in ascending date order

        cmd_template = 'log --date-order --reverse --pretty=format:"%H"'

        cmd_params = {}

        if start_date:

            cmd_template += ' --since "$since"'

            cmd_params['since'] = start_date.strftime('%m/%d/%y %H:%M:%S')

        if end_date:

            cmd_template += ' --until "$until"'

            cmd_params['until'] = end_date.strftime('%m/%d/%y %H:%M:%S')

        if branch_name:

            cmd_template += ' $branch_name'

            cmd_params['branch_name'] = branch_name

        else:

            cmd_template += ' --all'

        cmd = Template(cmd_template).safe_substitute(**cmd_params)

        revs = self.run_git_command(cmd)[0].splitlines()

        start_pos = 0

        end_pos = len(revs)

        if start:

            _start = self._get_revision(start)

            try:

                start_pos = revs.index(_start)

            except ValueError:

                pass

        if end is not None:

            _end = self._get_revision(end)

            try:

                end_pos = revs.index(_end)

            except ValueError:

                pass

        if None not in [start, end] and start_pos > end_pos:

            raise RepositoryError('start cannot be after end')

        if end_pos is not None:

            end_pos += 1

        revs = revs[start_pos:end_pos]

        if reverse:

            revs = reversed(revs)

        for rev in revs:

            yield self.get_changeset(rev)

    def get_diff(self, rev1, rev2, path=None, ignore_whitespace=False,

                 context=3):

        """

        Returns (git like) *diff*, as plain text. Shows changes introduced by

        ``rev2`` since ``rev1``.

        :param rev1: Entry point from which diff is shown. Can be

          ``self.EMPTY_CHANGESET`` - in this case, patch showing all

          the changes since empty state of the repository until ``rev2``

        :param rev2: Until which revision changes should be shown.

        :param ignore_whitespace: If set to ``True``, would not show whitespace

          changes. Defaults to ``False``.

        :param context: How many lines before/after changed lines should be

          shown. Defaults to ``3``.

        """

        flags = ['-U%s' % context, '--full-index', '--binary', '-p', '-M', '--abbrev=40']

        if ignore_whitespace:

            flags.append('-w')

        if hasattr(rev1, 'raw_id'):

            rev1 = getattr(rev1, 'raw_id')

        if hasattr(rev2, 'raw_id'):

            rev2 = getattr(rev2, 'raw_id')

        if rev1 == self.EMPTY_CHANGESET:

            rev2 = self.get_changeset(rev2).raw_id

            cmd = ' '.join(['show'] + flags + [rev2])

        else:

            rev1 = self.get_changeset(rev1).raw_id

            rev2 = self.get_changeset(rev2).raw_id

            cmd = ' '.join(['diff'] + flags + [rev1, rev2])

        if path:

            cmd += ' -- "%s"' % path

        stdout, stderr = self.run_git_command(cmd)

        # If we used 'show' command, strip first few lines (until actual diff

        # starts)

        if rev1 == self.EMPTY_CHANGESET:

            lines = stdout.splitlines()

            x = 0

            for line in lines:

                if line.startswith('diff'):

                    break

                x += 1

            # Append new line just like 'diff' command do

            stdout = '\n'.join(lines[x:]) + '\n'

        return stdout

    @LazyProperty

    def in_memory_changeset(self):

        """

        Returns ``GitInMemoryChangeset`` object for this repository.

        """

        return GitInMemoryChangeset(self)

    def clone(self, url, update_after_clone=True, bare=False):

        """

        Tries to clone changes from external location.

        :param update_after_clone: If set to ``False``, git won't checkout

          working directory

        :param bare: If set to ``True``, repository would be cloned into

          *bare* git repository (no working directory at all).

        """

        url = self._get_url(url)

        cmd = ['clone']

        if bare:

            cmd.append('--bare')

        elif not update_after_clone:

            cmd.append('--no-checkout')

        cmd += ['--', '"%s"' % url, '"%s"' % self.path]

        cmd = ' '.join(cmd)

        # If error occurs run_git_command raises RepositoryError already

        self.run_git_command(cmd)

    def pull(self, url):

        """

        Tries to pull changes from external location.

        """

        url = self._get_url(url)

        cmd = ['pull']

        cmd.append("--ff-only")

        cmd.append(url)

        cmd = ' '.join(cmd)

        # If error occurs run_git_command raises RepositoryError already

        self.run_git_command(cmd)

    def fetch(self, url):

        """

        Tries to pull changes from external location.

        """

        url = self._get_url(url)

        refs = []

        for line in (x for x in so.splitlines()):

            sha, ref = line.split('\t')

            refs.append(ref)

        refs = ' '.join(('+%s:%s' % (r, r) for r in refs))

        self.run_git_command(cmd)

    @LazyProperty

    def workdir(self):

        """

        Returns ``Workdir`` instance for this repository.

        """

        return GitWorkdir(self)

    def get_config_value(self, section, name, config_file=None):

        """

        Returns configuration value for a given [``section``] and ``name``.

        :param section: Section we want to retrieve value from

        :param name: Name of configuration we want to retrieve

        :param config_file: A path to file which should be used to retrieve

          configuration from (might also be a list of file paths)

        """

        if config_file is None:

            config_file = []

        elif isinstance(config_file, basestring):

            config_file = [config_file]

        def gen_configs():

            for path in config_file + self._config_files:

                try:

                    yield ConfigFile.from_path(path)

                except (IOError, OSError, ValueError):

                    continue

        for config in gen_configs():

            try:

                return config.get(section, name)

            except KeyError:

                continue

        return None

    def get_user_name(self, config_file=None):

        """

        Returns user's name from global configuration file.

        :param config_file: A path to file which should be used to retrieve

          configuration from (might also be a list of file paths)

        """

        return self.get_config_value('user', 'name', config_file)

    def get_user_email(self, config_file=None):

        """

        Returns user's email from global configuration file.

        :param config_file: A path to file which should be used to retrieve

          configuration from (might also be a list of file paths)

        """

        return self.get_config_value('user', 'email', config_file)