if rev:

            rev = safe_str(rev)

        if branch:

            branch = safe_str(branch)

        if branch_rev:

            branch_rev = safe_str(branch_rev)

            # a revset not restricting to merge() would be better

            # (especially because it would get the branch point)

            # ... but is currently too expensive

            # including branches of children could be nice too

            peerbranches = set()

            for i in repo._repo.revs(

                "sort(parents(branch(id(%s)) and merge()) - branch(id(%s)), -rev)",

                branch_rev, branch_rev):

                abranch = repo.get_changeset(i).branch

                if abranch not in peerbranches:

                    n = 'branch:%s:%s' % (abranch, repo.get_changeset(abranch).raw_id)

                    peers.append((n, abranch))

                    peerbranches.add(abranch)

        selected = None

        branches = []

        for abranch, branchrev in repo.branches.iteritems():

            n = 'branch:%s:%s' % (abranch, branchrev)

            if rev == branchrev:

                selected = n

            if branch == abranch:

                if not rev:

                    selected = n

                branch = None

        if branch:  # branch not in list - it is probably closed

            branchrev = repo.closed_branches.get(branch)

            if branchrev:

                n = 'branch:%s:%s' % (branch, branchrev)

                branches.append((n, _('%s (closed)') % branch))

                selected = n

                branch = None

            if branch:

                log.error('branch %r not found in %s', branch, repo)

        bookmarks = []

        for bookmark, bookmarkrev in repo.bookmarks.iteritems():

            n = 'book:%s:%s' % (bookmark, bookmarkrev)

            bookmarks.append((n, bookmark))

            if rev == bookmarkrev:

                selected = n

        tags = []

        for tag, tagrev in repo.tags.iteritems():

            n = 'tag:%s:%s' % (tag, tagrev)

            tags.append((n, tag))

                selected = n

        # prio 1: rev was selected as existing entry above

        # prio 2: create special entry for rev; rev _must_ be used

        specials = []

        if rev and selected is None:

            selected = 'rev:%s:%s' % (rev, rev)

            specials = [(selected, '%s: %s' % (_("Changeset"), rev[:12]))]

        # prio 3: most recent peer branch

        if peers and not selected:

            selected = peers[0][0][0]

        # prio 4: tip revision

        if not selected:

            if h.is_hg(repo):

                else:

                    selected = 'tag:null:0'

                    tags.append((selected, 'null'))

            else:

                if 'master' in repo.branches:

                    selected = 'branch:master:%s' % repo.branches['master']

                else:

                    k, v = repo.branches.items()[0]

                    selected = 'branch:%s:%s' % (k, v)

        groups = [(specials, _("Special")),

                  (peers, _("Peer branches")),

                  (bookmarks, _("Bookmarks")),

                  (branches, _("Branches")),

                  (tags, _("Tags")),

                  ]

        return [g for g in groups if g[0]], selected

    def _get_is_allowed_change_status(self, pull_request):

        owner = self.authuser.user_id == pull_request.user_id

        reviewer = self.authuser.user_id in [x.user_id for x in

                                                   pull_request.reviewers]

        return self.authuser.admin or owner or reviewer