mutter 3.38.1 breaks xhost

Affected version

• mutter 3.38.1, probably also mutter 3.38.0
• issue appears only on Wayland; XOrg works fine

Bug summary

Many Gnome on Wayland users rely on xhost for running GUI applications that require root privileges, e.g. GParted. This is probably the main but not only use case. According to this email thread this commit !1424 (merged) caused the regression.

I'm not aware of an alternative xhost-like tool for Wayland and therefore consider this to be a bug because it breaks workflows that have been working properly before.

Steps to reproduce

xhost +si:localuser:$USER
su - $USER
gparted

What happened

Unable to init server: Could not connect: Connection refused

Error: cannot open display: :0

What did you expect to happen

GParted to be successfully started.