_usr = self._get_user(uid)

            reviewer = PullRequestReviewers(_usr, pull_request)

            Session().add(reviewer)

        for uid in to_remove:

            reviewer = PullRequestReviewers.query()\

                    .filter(PullRequestReviewers.user_id==uid,

                            PullRequestReviewers.pull_request==pull_request)\

                    .scalar()

            if reviewer:

                Session().delete(reviewer)

    def delete(self, pull_request):

        pull_request = self.__get_pull_request(pull_request)

        Session().delete(pull_request)

    def close_pull_request(self, pull_request):

        pull_request = self.__get_pull_request(pull_request)

        pull_request.status = PullRequest.STATUS_CLOSED

        pull_request.updated_on = datetime.datetime.now()

        Session().add(pull_request)

    def _get_changesets(self, alias, org_repo, org_ref, other_repo, other_ref, merge):

        """

        Returns a list of changesets that can be merged from org_repo@org_ref

        to other_repo@other_ref ... and the ancestor that would be used for merge

        :param org_repo:

        :param org_ref:

        :param other_repo:

        :param other_ref:

        :param tmp:

        """

        ancestor = None

        if alias == 'hg':

            # lookup up the exact node id

            _revset_predicates = {

                    'branch': 'branch',

                    'book': 'bookmark',

                    'tag': 'tag',

                    'rev': 'id',

                }

            org_rev_spec = "%s('%s')" % (_revset_predicates[org_ref[0]],

                                         safe_str(org_ref[1]))

            org_revs = scmutil.revrange(org_repo._repo, [org_rev_spec])

            other_rev_spec = "%s('%s')" % (_revset_predicates[other_ref[0]],

                                           safe_str(other_ref[1]))

            other_revs = scmutil.revrange(other_repo._repo, [other_rev_spec])

            #case two independent repos

            if org_repo != other_repo:

                hgrepo = unionrepo.unionrepository(other_repo.baseui,

                                                   other_repo.path,

                                                   org_repo.path)

                # all the changesets we are looking for will be in other_repo,

                # so rev numbers from hgrepo can be used in other_repo

            #no remote compare do it on the same repository

            else:

                hgrepo = other_repo._repo

            if merge:

                revs = ["ancestors(id('%s')) and not ancestors(id('%s')) and not id('%s')" %

                        (other_rev, org_rev, org_rev)]

                ancestors = scmutil.revrange(hgrepo,

                     ["ancestor(id('%s'), id('%s'))" % (org_rev, other_rev)])

                if len(ancestors) == 1:

                    ancestor = hgrepo[ancestors[0]].hex()

            else:

                # TODO: have both + and - changesets

                revs = ["id('%s') :: id('%s') - id('%s')" %

                        (org_rev, other_rev, org_rev)]

            changesets = [other_repo.get_changeset(cs)

                          for cs in scmutil.revrange(hgrepo, revs)]

        elif alias == 'git':

            assert org_repo == other_repo, (org_repo, other_repo) # no git support for different repos

            so, se = org_repo.run_git_command(

                'log --reverse --pretty="format: %%H" -s -p %s..%s' % (org_ref[1],

                                                                       other_ref[1])

            )

            changesets = [org_repo.get_changeset(cs)

                          for cs in re.findall(r'[0-9a-fA-F]{40}', so)]

        return changesets, ancestor

    def get_compare_data(self, org_repo, org_ref, other_repo, other_ref, merge):

        """

        Returns incoming changesets for mercurial repositories

        :param org_repo:

        :param org_ref:

        :param other_repo:

        :param other_ref: