TYPO3 Core

The Problem:

I´ve installed TYPO3 in a subfolder e.g.: The apache webroot D:\wamp\www\customer\project

The siteconfig entry point and the resulting base-href-uri is

http://localhost/customer/project/public/

The generated Links/Slugs in Typo v9 in navigation (menu-processor/fluid) or JS/CSS-resources are:

<a href="/customer/project/public/link_or_slugname">

The browsers accept these "double path scheme" to an resulting correct path, but other "internal" tools in our projects recognizes
such paths as
http://localhost/customer/project/public//customer/project/public/link_or_slugname

Typo 7.6 generated such links correct as "really" relative, only the Link/Slug without prefixed slash and sub-path,
e.g.
<a href="link_or_slugname/">

My question: Is this a miss-config by me or a possible bug in url-generation of Typo V9?

Best regards
Ralf