Failed to resolve unit specifiers on 100%VG: Invalid slot

[cndbain]

I updated the CoreOS AMI ID for a cluster using raid0Mounts and started seeing errors like:

Jan 09 19:22:16 ip-10-23-41-50.us-west-2.compute.internal bash[1296]: 2019/01/09 19:22:16 Calling unit command "start" on "format-data.service"
Jan 09 19:22:16 ip-10-23-41-50.us-west-2.compute.internal systemd[1]: /etc/systemd/system/format-data.service:10: Failed to resolve unit specifiers on 100%VG: Invalid slot
Jan 09 19:22:16 ip-10-23-41-50.us-west-2.compute.internal bash[1296]: 2019/01/09 19:22:16 Failed to apply cloud-config: Unit format-data.service is not loaded properly: Exec >

When trying to bring up new instances. It turns out this is due to a change in systemd that disallows unknown % characters:

https://github.com/systemd/systemd/blob/a1b2c92d8290c76a29ccd0887a92ac064e1bb5a1/NEWS#L10

I'll add a pull request that escapes the % character.