# prio 4: tip revision

        if not selected:

            if h.is_hg(repo):

                if tipbranch:

                    selected = 'branch:%s:%s' % (tipbranch, tiprev)

                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

    def _load_compare_data(self, pull_request, enable_comments=True):

        """

        Load context data needed for generating compare diff

        :param pull_request:

        """

        c.org_repo = pull_request.org_repo

        (c.org_ref_type,

         c.org_ref_name,

         c.org_rev) = pull_request.org_ref.split(':')

        c.other_repo = pull_request.other_repo

        (c.other_ref_type,

         c.other_ref_name,

         c.other_rev) = pull_request.other_ref.split(':') # other_rev is ancestor

        org_scm_instance = c.org_repo.scm_instance # property with expensive cache invalidation check!!!

        c.cs_repo = c.org_repo

        c.cs_ranges = [org_scm_instance.get_changeset(x) for x in pull_request.revisions]