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

        if message is None:

            message = "Removed tag %s" % name

        if date is None:

            date = datetime.datetime.now().ctime()

        local = False

        try:

            self._repo.tag(name, nullid, message, local, user, date)

            self.tags = self._get_tags()

        except Abort, e:

            raise RepositoryError(e.message)

    @LazyProperty

    def bookmarks(self):

        """

        Get's bookmarks for this repository

        """

        return self._get_bookmarks()

    def _get_bookmarks(self):

        if self._empty:

            return {}

        sortkey = lambda ctx: ctx[0]  # sort by name

        _bookmarks = [(safe_unicode(n), hex(h),) for n, h in

                 self._repo._bookmarks.items()]

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

    def _get_all_revisions(self):

        return map(lambda x: hex(x[7]), self._repo.changelog.index)[:-1]

    def get_diff(self, rev1, rev2, path='', 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``.

        """

        # Check if given revisions are present at repository (may raise

        # ChangesetDoesNotExistError)

        if rev1 != self.EMPTY_CHANGESET:

            self.get_changeset(rev1)

        self.get_changeset(rev2)

        file_filter = match(self.path, '', [path])

        return ''.join(patch.diff(self._repo, rev1, rev2, match=file_filter,

                          opts=diffopts(git=True,

                                        ignorews=ignore_whitespace,

                                        context=context)))

    def _check_url(self, url):

        """

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

        link. Sometimes it may happened that mercurial 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, return code 200 if url

        is valid or True if it's a local path

        """

        from mercurial.util import url as Url

        # those authnadlers are patched for python 2.6.5 bug an

        # infinit looping when given invalid resources

        from mercurial.url import httpbasicauthhandler, httpdigestauthhandler

        # check first if it's not an local url

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

            return True

        handlers = []

        test_uri, authinfo = Url(url).authinfo()

        if authinfo:

            #create a password manager

            passmgr = urllib2.HTTPPasswordMgrWithDefaultRealm()

            passmgr.add_password(*authinfo)

            handlers.extend((httpbasicauthhandler(passmgr),

                             httpdigestauthhandler(passmgr)))

        o = urllib2.build_opener(*handlers)

        o.addheaders = [('Content-Type', 'application/mercurial-0.1'),

                        ('Accept', 'application/mercurial-0.1')]