uri = uri_filter(uri)

    # check if we have port

    if len(uri) > 2 and uri[2]:

        uri[2] = ':' + uri[2]

    return ''.join(uri)

def get_clone_url(clone_uri_tmpl, prefix_url, repo_name, repo_id, username=None):

    parsed_url = urlobject.URLObject(prefix_url)

    prefix = safe_unicode(urllib.unquote(parsed_url.path.rstrip('/')))

    args = {

        'scheme': parsed_url.scheme,

        'user': safe_unicode(urllib.quote(safe_str(username or ''))),

        'netloc': parsed_url.netloc + prefix,  # like "hostname:port/prefix" (with optional ":port" and "/prefix")

        'prefix': prefix, # undocumented, empty or starting with /

        'repo': repo_name,

        'repoid': str(repo_id),

    }

    url = re.sub('{([^{}]+)}', lambda m: args.get(m.group(1), m.group(0)), clone_uri_tmpl)

    # remove leading @ sign if it's present. Case of empty user

    url_obj = urlobject.URLObject(url)

def get_changeset_safe(repo, rev):

    """

    Safe version of get_changeset if this changeset doesn't exists for a

    repo it returns a Dummy one instead

    :param repo:

    :param rev:

    """

    from kallithea.lib.vcs.backends.base import BaseRepository

    from kallithea.lib.vcs.exceptions import RepositoryError

    from kallithea.lib.vcs.backends.base import EmptyChangeset

    if not isinstance(repo, BaseRepository):

        raise Exception('You must pass an Repository '

                        'object as first argument got %s', type(repo))

    try:

        cs = repo.get_changeset(rev)

    except (RepositoryError, LookupError):

        cs = EmptyChangeset(requested_revision=rev)

    return cs