Using a proxy doesn't honor no proxy hosts

When a proxy is set in Jenkins the HttpClient of the repoclient uses the proxy settings but it does not honor the no proxy hosts settings. All requests will use the proxy. In a setup where a proxy needs to be set to access outside server, e.g. for plugin installation, but the Nexus repository is hosted on-site behind the firewall and should not use the proxy, the plugin will not work.
