siteBaseUrl option doesn't work as expected

[getbored]

Hi! Sorry to bother you.
I've installed the latest version of private-bower.
I use the default configuration and only change "siteBaseUrl" value:

...
{
    "registryFile": "./bowerRepository.json",
    "timeout": 144000,
    "server": {
        "port": 5678,
        "hostName": null,
        "siteBaseUrl": "/private-bower"
    },
...

Maybe I'm doing something wrong, but the "siteBaseUrl" option doesn't work for me.
I got the following response when trying to reach the page via curl or browser:

[www-data@host]$ curl 127.0.0.1:5678/private-bower
Cannot GET /private-bower

At the same time I can successfully get 127.0.0.1:5678 and 127.0.0.1:5678/packages

What am I doing wrong, could someone please advice?

Thanks!