fix(configdrive): Always run after OEM and ec2 metadata.

A workaround for https://github.com/coreos/coreos-cloudinit/issues/86

Longer term cloudinit needs to be fixed to not corrupt the system when
multiple config sources are being used. We've pretty much gotten this
far without this coming up because most configs don't conflict so badly.

units/user-cloudinit@media-configdrive-openstack-latest-user_data.service

@@ -0,0 +1,24 @@
+[Unit]
+Description=Load cloud-config from %f
+Requires=coreos-setup-environment.service
+After=coreos-setup-environment.service
+Before=user-config.target
+ConditionFileNotEmpty=%f
+
+# HACK: work around ordering between config drive and ec2 metadata It is
+# possible for OpenStack style systems to provide both the metadata service
+# and config drive, to prevent the two from stomping on eachother force
+# this to run after OEM and after metadata (if it exsts). I'm doing this
+# here instead of in the ec2 service because the ec2 unit is not written
+# to disk until the OEM cloud config is evaluated and I want to make sure
+# systemd knows about the ordering as early as possible.
+# coreos-cloudinit could implement a simple lock but that cannot be used
+# until after the systemd dbus calls are made non-blocking.
+After=system-cloudinit@usr-share-oem-cloud\x2dconfig.yml.service
+After=ec2-cloudinit.service
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+EnvironmentFile=-/etc/environment
+ExecStart=/usr/bin/coreos-cloudinit --from-file=%f