"""return a structure with repo's interesting changesets, suitable for

        the selectors in pullrequest.html

        rev: a revision that must be in the list somehow and selected by default

        branch: a branch that must be in the list and selected by default - even if closed

        branch_rev: a revision of which peers should be preferred and available."""

        # list named branches that has been merged to this named branch - it should probably merge back

        peers = []

        if rev:

            rev = safe_str(rev)

        if branch:

            branch = safe_str(branch)

        if branch_rev:

            branch_rev = safe_str(branch_rev)

            # not restricting to merge() would also get branch point and be better

            # (especially because it would get the branch point) ... but is currently too expensive

            otherbranches = {}

            for i in repo._repo.revs(

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

                branch_rev, branch_rev):

                cs = repo.get_changeset(i)

            for abranch, node in otherbranches.iteritems():

                selected = 'branch:%s:%s' % (abranch, node)

                peers.append((selected, abranch))

        selected = None

        branches = []

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

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

            branches.append((n, abranch))

            if rev == branchrev:

                selected = n

            if branch == abranch:

                selected = n

                branch = None

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

            revs = repo._repo.revs('max(branch(%s))', branch)

            if revs:

                cs = repo.get_changeset(revs[0])

                selected = 'branch:%s:%s' % (branch, cs.raw_id)

                branches.append((selected, branch))

        bookmarks = []