attribute allows external tools to inject shas from cache.

        """

        return self._get_all_revisions()

    def run_git_command(self, cmd):

        """

        Runs given ``cmd`` as git command and returns tuple

        (returncode, stdout, stderr).

        .. note::

           This method exists only until log/blame functionality is implemented

           at Dulwich (see https://bugs.launchpad.net/bugs/645142). Parsing

           os command's output is road to hell...

        :param cmd: git command to be executed

        """

        _copts = ['-c', 'core.quotepath=false', ]

        _str_cmd = False

        if isinstance(cmd, basestring):

            cmd = [cmd]

            _str_cmd = True

        gitenv = os.environ

        gitenv['GIT_CONFIG_NOGLOBAL'] = '1'

        cmd = ['git'] + _copts + cmd

        if _str_cmd:

            cmd = ' '.join(cmd)

        try:

            opts = dict(

                shell=isinstance(cmd, basestring),

                stdout=PIPE,

                stderr=PIPE,

                env=gitenv,

            )

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

                opts['cwd'] = self.path

            p = Popen(cmd, **opts)

        except OSError, err:

            raise RepositoryError("Couldn't run git command (%s).\n"

                "Original error was:%s" % (cmd, err))

        so, se = p.communicate()

        if not se.startswith("fatal: bad default revision 'HEAD'") and \

            p.returncode != 0:

            raise RepositoryError("Couldn't run git command (%s).\n"

                "stderr:\n%s" % (cmd, se))

        return so, se