Hi Guix, An unfortunate chain of propagated-inputs causes 'util-linux' (mount, umount, etc.) to be installed alongside 'mps-youtube': 'mps-youtube' propagates 'python-pygobject', which propagates 'glib', which propagates 'util-linux'. It seems to have been introduced with commit 6c237a2, when 'util-linux' was moved to the propagated-inputs of 'glib'.
This is a problem on foreign distributions, where the stowaway 'mount' and 'umount' commands installed by Guix shadow the setuid ones provided by the distro. I am currently on commit ecf3a3a (post core-updates merge). Regards, Diego