So I’ve googled on trying to remove this yahoo search home page (with spigot in the querystring).
I did not find any extensions that could have contained spigot (but perhaps I did remove one months ago) and also did not find anything in any LaunchAgent or LaunchDaemon folder.
However, in ~/Library/Application Support/Google/Chrome/Default there’s a file called Preferences which contains a large json blob with two instances of the yahoo url listed. Edit out those urls (I simple removed the urls so that chrome will start empty).
Problem solved.