While testing #12019 I noticed I get the error

INFO [2017-09-08 12:16:39] Unable to test if mod_pagespeed is enabled: the request to http://unknown/./console?module=Installation&action=getEmptyPageForSystemCheck failed

when executing ./console diagnostics:run

I searched for similar issues but they seem different. Seems like Url::getCurrentUrlWithoutQueryString() does not return a URL.