I noticed that while YaST runs, (/mnt)/run of the target system is bind mounted
on top of /run.
This impacts the live environment badly, as it's pretty much unusuable without
dbus and wayland sockets and so on...

/proc/self/mountinfo shows:

644 577 0:24 / /mnt/run rw,nosuid,nodev shared:24 - tmpfs tmpfs
rw,size=802844k,nr_inodes=819200,mode=755,inode64
661 644 0:24 / /mnt/run rw,nosuid,nodev shared:24 - tmpfs tmpfs
rw,size=802844k,nr_inodes=819200,mode=755,inode64
662 28 0:24 / /run rw,nosuid,nodev shared:24 - tmpfs tmpfs
rw,size=802844k,nr_inodes=819200,mode=755,inode64

So it seems like YaST basically does:

mount -t tmpfs tmpfs /mnt/run
mount --bind /mnt/run /mnt/run
mount --bind /mnt/run /run

Why not just mount --bind /run /mnt/run?