0.91.0 obsoletes gnome-system-tools-0.34.0-fix-nopasswd-auth.patch. Removing src_unpack completely works here.
Perhaps there should be a USE flag to enable the optional tools that were disabled by default in this release?
gnome-system-tools-0.92.0 was just released. I version-bumped the gnome-system-tools-0.34.0-r1.ebuild to gnome-system-tools-0.92.0.ebuild, and removed src_unpack(). It works for me. Concerning the USE flags, the default configuration in 0.92.0 didn't --enable-disks. When I tried to enable it (by appending EXTRA_ECONF="--enable-boot --enable-network --enable-services --enable-time --enable-users --enable-disks"), I obtained the "Disks" within System Settings. When I double-clicked Disks, it says "The platform you are running is not supported by this tool". So I guess, at least for now, I wouldn't --enable-disks. But I can imagine associating --enable-time with ntp.
Version 0.92.0 is now in the tree. Thank you for your report.