# prev link

        try:

            prev_rev = c.db_repo_scm_instance.get_changeset(cur_rev).prev(c.branch)

            c.url_prev = url('files_home', repo_name=c.repo_name,

                         revision=prev_rev.raw_id, f_path=f_path)

            if c.branch:

                c.url_prev += '?branch=%s' % c.branch

        except (ChangesetDoesNotExistError, VCSError):

            c.url_prev = '#'

        # next link

        try:

            next_rev = c.db_repo_scm_instance.get_changeset(cur_rev).next(c.branch)

            c.url_next = url('files_home', repo_name=c.repo_name,

                     revision=next_rev.raw_id, f_path=f_path)

            if c.branch:

                c.url_next += '?branch=%s' % c.branch

        except (ChangesetDoesNotExistError, VCSError):

            c.url_next = '#'

        # files or dirs

        try:

            c.file = c.changeset.get_node(f_path)

                c.load_full_history = False

                # determine if we're on branch head

                _branches = c.db_repo_scm_instance.branches

                c.on_branch_head = revision in _branches.keys() + _branches.values()

                _hist = []

                c.file_history = []

                if c.load_full_history:

                    c.file_history, _hist = self._get_node_history(c.changeset, f_path)

                c.authors = []

                for a in set([x.author for x in _hist]):

                    c.authors.append((h.email(a), h.person(a)))

            else:

                c.authors = c.file_history = []

        except RepositoryError as e:

            h.flash(safe_str(e), category='error')

            raise HTTPNotFound()

        if request.environ.get('HTTP_X_PARTIAL_XHR'):

            return render('files/files_ypjax.html')

        # TODO: tags and bookmarks?

        c.revision_options = [(c.changeset.raw_id,

                              _('%s at %s') % (b, h.short_id(c.changeset.raw_id))) for b in c.changeset.branches] + \

        # GIT_REPO should be untouched for other tests so create a fork

        fork_name = '%s_fork%s' % (GIT_REPO, _RandomNameSequence().next())

        fixture.create_fork(GIT_REPO, fork_name)

        fork_url = webserver.repo_url(fork_name)

        # add submodule

        stdout, stderr = Command(TESTS_TMP_PATH).execute('git clone', fork_url, dest_dir)

        stdout, stderr = Command(dest_dir).execute('git submodule add', clone_url, 'testsubmodule')

        stdout, stderr = Command(dest_dir).execute('git commit -am "added testsubmodule pointing to', clone_url, '"')

        stdout, stderr = Command(dest_dir).execute('git push', fork_url, 'master')

        # check for testsubmodule link in files page

        self.log_user()

        response = self.app.get(url(controller='files', action='index',

                                    repo_name=fork_name,

                                    revision='tip',

                                    f_path='/'))

        response.mustcontain('<a class="submodule-dir" href="%s"><i class="icon-file-submodule"></i><span>testsubmodule @ ' % clone_url)

        # check that following a submodule link actually works - and redirects

        response = self.app.get(url(controller='files', action='index',

                                    repo_name=fork_name,

                                    revision='tip',

                                    f_path='/testsubmodule'),