On todays machines /etc/hosts is not mandatory. /etc/machine-id is though, so let's rely on that instead.
This makes the udev tests pass again for me.
devpath => "/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda",
exp_name => "there",
rules => <<EOF
-TEST=="/etc/hosts", SYMLINK+="there"
-TEST!="/etc/hosts", SYMLINK+="notthere"
+TEST=="/etc/machine-id", SYMLINK+="there"
+TEST!="/etc/machine-id", SYMLINK+="notthere"
EOF
},
{