mdadm-last-resort@.service runs when array is active

In testing, a raid5 array is started and mounted, but at some point the <email address hidden> is triggered and unmounts the raid device.

This is fixed upstream with:

https://github.com/neilbrown/mdadm/commit/5c4b3b9aa9f576305b36d5ccbd4b929b51307ce9

1. ubuntu@ubuntu:~$ lsb_release -rd
Description: Ubuntu 17.10
Release: 17.10

2. ubuntu@ubuntu:~$ apt-cache policy mdadm
mdadm:
  Installed: 4.0-2
  Candidate: 4.0-2
  Version table:
 *** 4.0-2 500
        500 http://archive.ubuntu.com/ubuntu artful/main amd64 Packages
        100 /var/lib/dpkg/status
3. /dev/md0 stays mounted after boot
4. /dev/md0 is unmounted from the system due to <email address hidden> running

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: mdadm 4.0-2 [modified: lib/systemd/system/mdadm-last-resort@.service]
ProcVersionSignature: User Name 4.13.0-36.40-generic 4.13.13
Uname: Linux 4.13.0-36-generic x86_64
ApportVersion: 2.20.7-0ubuntu3.7
Architecture: amd64
Date: Tue Mar 6 16:03:25 2018
Lsusb: Error: command ['lsusb'] failed with exit code 1:
MDadmExamine.dev.sda: Error: command ['/sbin/mdadm', '-E', '/dev/sda'] failed with exit code 1: mdadm: cannot open /dev/sda: Permission denied
MDadmExamine.dev.sdb: Error: command ['/sbin/mdadm', '-E', '/dev/sdb'] failed with exit code 1: mdadm: cannot open /dev/sdb: Permission denied
MDadmExamine.dev.sdc: Error: command ['/sbin/mdadm', '-E', '/dev/sdc'] failed with exit code 1: mdadm: cannot open /dev/sdc: Permission denied
MachineType: QEMU Standard PC (i440FX + PIIX, 1996)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=C.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.13.0-36-generic root=UUID=413f8b88-2156-11e8-93a3-525400123400 ro console=ttyS0
ProcMDstat:
 Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
 md0 : active raid5 sdc[1] sdb[0] sda[3]
       10477568 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]

 unused devices: <none>
SourcePackage: mdadm
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/01/2014
dmi.bios.vendor: SeaBIOS
dmi.bios.version: 1.10.2-1ubuntu1
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: pc-i440fx-bionic
dmi.modalias: dmi:bvnSeaBIOS:bvr1.10.2-1ubuntu1:bd04/01/2014:svnQEMU:pnStandardPC(i440FX+PIIX,1996):pvrpc-i440fx-bionic:cvnQEMU:ct1:cvrpc-i440fx-bionic:
dmi.product.name: Standard PC (i440FX + PIIX, 1996)
dmi.product.version: pc-i440fx-bionic
dmi.sys.vendor: QEMU
etc.blkid.tab: Error: [Errno 2] No such file or directory: '/etc/blkid.tab'
mdadm.conf:
 ARRAY /dev/md0 metadata=1.2 spares=1 name=ubuntu:0 UUID=aefcb03c:f7588463:d51ac0c1:3dfa8d62
 MAILADDR root