Merge nucleic/olive-willow-newt-96nb into dev

tests/smoke-rootfs.sh

@@ -95,7 +95,11 @@ case "$FLAVOR" in
       test -x /usr/local/bin/nucleic-a11y-agent
       test -x /usr/local/bin/nucleic-linux-agent
       test -f /usr/share/gnome-shell/extensions/[email protected]/metadata.json
-      grep -q "AutomaticLogin=agent" /etc/gdm3/daemon.conf'
+      grep -q "AutomaticLogin=agent" /etc/gdm3/daemon.conf
+      # Swift comes from forky swiftlang here (vm-desktop.pkgs), so assert the compiler
+      # actually loads — a soname drift in the pocket (the libxml2 .so.2→.so.16 kind) would
+      # otherwise ship a Swift that only fails the first time an agent invokes it.
+      swiftc --version > /dev/null'
     ;;
 
   *)