I also performed an upgrade from Ubuntu 16.04, with the apt-clone file restored, to Ubuntu 18.04 using the dist-upgrader from -proposed.. The upgrade proceeded without error and libc6 was installed first.
bdmurray@clean-xenial-amd64:~$ grep -n "libc6\|gnome-menus" /var/log/dist-upgrade/apt-term.log 9:Preparing to unpack .../libc6-dev_2.27-3ubuntu1_amd64.deb ... 10:Unpacking libc6-dev:amd64 (2.27-3ubuntu1) over (2.23-0ubuntu10) ... 11:Preparing to unpack .../libc6-dbg_2.27-3ubuntu1_amd64.deb ... 12:Unpacking libc6-dbg:amd64 (2.27-3ubuntu1) over (2.23-0ubuntu10) ... 15:Preparing to unpack .../libc6_2.27-3ubuntu1_amd64.deb ... 19:Unpacking libc6:amd64 (2.27-3ubuntu1) over (2.23-0ubuntu10) ... 20:Setting up libc6:amd64 (2.27-3ubuntu1) ... 32:Preparing to unpack .../libc6-i386_2.27-3ubuntu1_amd64.deb ... 33:Unpacking libc6-i386 (2.27-3ubuntu1) over (2.23-0ubuntu10) ... 36:Setting up libc6-dev:amd64 (2.27-3ubuntu1) ... 37:Setting up libc6-dbg:amd64 (2.27-3ubuntu1) ... 59:Setting up libc6-i386 (2.27-3ubuntu1) ... 224:Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ... 237:Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ... 305:Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ... 701:dpkg: gnome-menus: dependency problems, but processing triggers anyway as you requested: 702: gnome-menus depends on python3:any (>= 3.1~); however: 705:Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ... 4150:Preparing to unpack .../gnome-menus_3.13.3-11ubuntu1.1_amd64.deb ... 4151:Unpacking gnome-menus (3.13.3-11ubuntu1.1) over (3.13.3-6ubuntu3.1) ... 12060:Setting up gnome-menus (3.13.3-11ubuntu1.1) ... 14849:Processing triggers for gnome-menus (3.13.3-11ubuntu1.1) ... 14901:Processing triggers for gnome-menus (3.13.3-11ubuntu1.1) ... 14923:Processing triggers for gnome-menus (3.13.3-11ubuntu1.1) ... -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1766890 Title: package gnome-menus 3.13.3-6ubuntu3.1 failed to install/upgrade: triggers looping, abandoned To manage notifications about this bug go to: https://bugs.launchpad.net/oem-priority/+bug/1766890/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs