SubprocessGitClient(thin_packs=False).fetch(org_repo.path, gitrepo_remote)

                revs = []

                for x in gitrepo_remote.get_walker(include=[other_rev],

                                                   exclude=[org_rev]):

                    revs.append(x.commit.id)

                other_changesets = [other_repo.get_changeset(rev) for rev in reversed(revs)]

                if other_changesets:

                    ancestor = other_changesets[0].parents[0].raw_id

                else:

                    # no changesets from other repo, ancestor is the other_rev

                    ancestor = other_rev

            else:

                so, se = org_repo.run_git_command(

                    ['log', '--reverse', '--pretty=format:%H',

                     '-s', '%s..%s' % (org_rev, other_rev)]

                )

                other_changesets = [org_repo.get_changeset(cs)

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

                so, se = org_repo.run_git_command(

                    ['merge-base', org_rev, other_rev]

                )

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

            org_changesets = []

        else:

            raise Exception('Bad alias only git and hg is allowed')

        return other_changesets, org_changesets, ancestor

    @LoginRequired()

    @HasRepoPermissionAnyDecorator('repository.read', 'repository.write',

                                   'repository.admin')

    def index(self, repo_name):

        c.compare_home = True

        org_repo = c.db_repo.repo_name

        other_repo = request.GET.get('other_repo', org_repo)

        c.a_repo = Repository.get_by_repo_name(org_repo)

        c.cs_repo = Repository.get_by_repo_name(other_repo)

        c.a_ref_name = c.cs_ref_name = _('Select changeset')

        return render('compare/compare_diff.html')

    @LoginRequired()

    @HasRepoPermissionAnyDecorator('repository.read', 'repository.write',

                                   'repository.admin')

    def compare(self, repo_name, org_ref_type, org_ref_name, other_ref_type, other_ref_name):

        org_repo = c.db_repo.repo_name

        other_repo = request.GET.get('other_repo', org_repo)

        # If merge is True:

        #   Show what org would get if merged with other:

        #   List changesets that are ancestors of other but not of org.

        #   New changesets in org is thus ignored.

        #   Diff will be from common ancestor, and merges of org to other will thus be ignored.

        # If merge is False:

        #   Make a raw diff from org to other, no matter if related or not.

        #   Changesets in one and not in the other will be ignored

        merge = bool(request.GET.get('merge'))

        # fulldiff disables cut_off_limit

        c.fulldiff = request.GET.get('fulldiff')

        # partial uses compare_cs.html template directly

        partial = request.environ.get('HTTP_X_PARTIAL_XHR')

        # as_form puts hidden input field with changeset revisions

        c.as_form = partial and request.GET.get('as_form')

        # swap url for compare_diff page - never partial and never as_form

        c.swap_url = h.url('compare_url',

            repo_name=other_repo,

            org_ref_type=other_ref_type, org_ref_name=other_ref_name,

            other_repo=org_repo,

            other_ref_type=org_ref_type, other_ref_name=org_ref_name,

            merge=merge or '')

        # set callbacks for generating markup for icons

        c.ignorews_url = _ignorews_url

        c.context_url = _context_url

        ignore_whitespace = request.GET.get('ignorews') == '1'

        line_context = request.GET.get('context', 3)

        org_repo = Repository.get_by_repo_name(org_repo)

        other_repo = Repository.get_by_repo_name(other_repo)

        if org_repo is None:

            msg = 'Could not find org repo %s' % org_repo

            log.error(msg)

            h.flash(msg, category='error')

            return redirect(url('compare_home', repo_name=c.repo_name))

        if other_repo is None:

            msg = 'Could not find other repo %s' % other_repo

            log.error(msg)

            h.flash(msg, category='error')

            return redirect(url('compare_home', repo_name=c.repo_name))

        if org_repo.scm_instance.alias != other_repo.scm_instance.alias:

            msg = 'compare of two different kind of remote repos not available'