Unexpected action output while using Juju 2.7

Problem description: Some new (unexpected) fields in the action output ("Stderr"/"Stdout") are present when executing an action on 2.7+ controller.

Bundle used: http://paste.ubuntu.com/p/vY338GDHMf/

=== Evidence ===

# Juju 2.6

ubuntu@OrangeBox84:~/fce-demo$ juju status
Model Controller Cloud/Region Version SLA Timestamp
vault foundations-maas maas_cloud 2.6.10 unsupported 14:15:02Z

App Version Status Scale Charm Store Rev OS Notes
easyrsa 3.0.1 active 1 easyrsa jujucharms 296 ubuntu
etcd 3.2.10 active 1 etcd jujucharms 496 ubuntu
mysql 5.7.20 active 3 percona-cluster jujucharms 284 ubuntu
vault 1.1.1 active 1 vault jujucharms 36 ubuntu

Unit Workload Agent Machine Public address Ports Message
easyrsa/0* active idle 0/lxd/0 172.27.85.128 Certificate Authority connected.
etcd/0* active idle 0/lxd/1 172.27.85.130 2379/tcp Healthy with 1 known peer
mysql/0 active idle 1/lxd/0 172.27.85.129 3306/tcp Unit is ready
mysql/1* active idle 0/lxd/2 172.27.85.133 3306/tcp Unit is ready
mysql/2 active idle 1/lxd/2 172.27.85.132 3306/tcp Unit is ready
vault/0* active idle 1/lxd/1 172.27.85.131 8200/tcp Unit is ready (active: true, mlock: disabled)

Machine State DNS Inst id Series AZ Message
0 started 172.27.85.126 node01 bionic default Deployed
0/lxd/0 started 172.27.85.128 juju-955a77-0-lxd-0 bionic default Container started
0/lxd/1 started 172.27.85.130 juju-955a77-0-lxd-1 bionic default Container started
0/lxd/2 started 172.27.85.133 juju-955a77-0-lxd-2 bionic default Container started
1 started 172.27.85.127 node02 bionic default Deployed
1/lxd/0 started 172.27.85.129 juju-955a77-1-lxd-0 bionic default Container started
1/lxd/1 started 172.27.85.131 juju-955a77-1-lxd-1 bionic default Container started
1/lxd/2 started 172.27.85.132 juju-955a77-1-lxd-2 bionic default Container started

ubuntu@OrangeBox84:~/fce-demo$ juju run-action vault/leader get-csr --wait
unit-vault-0:
  id: b23e2ed9-4b98-4849-865c-b374c2bb12d3
  results:
    output: |-
      -----BEGIN CERTIFICATE REQUEST-----
      MIICijCCAXICAQAwRTFDMEEGA1UEAxM6VmF1bHQgSW50ZXJtZWRpYXRlIENlcnRp
      ZmljYXRlIEF1dGhvcml0eSAoY2hhcm0tcGtpLWxvY2FsKTCCASIwDQYJKoZIhvcN
      AQEBBQADggEPADCCAQoCggEBAOMzPg4DxTt/0DptbT9lQRm7FrBHw2Q6LlhPW7Ca
      jTbN/rO329/xIDcTgAZeqOPoGl5Wm48bRVYr2877MXfxJcGpqbIKkxu1z9AKddNa
      QptSQ+kokF4H4VX7vfYaNPTbtob6VWLx+BwqiVB5yR6RqMvzkiUlYAsKJ2PiuaJ5
      pEf7aQ46FhGrpSZJvbJZ9WZu5wbrjWSHSfSF1OEYdPm9gOfYazGq8aBuZRbdg5bu
      dH+lHo4OuaRqaTfgL3d/M+D/yIEIXs7fzMDHyhBxi5/YQgrl5xGjHbMbX1DWPkeN
      gRWahaUwgQy4nJAdn1kQHfGn2gcEKJ7hN4HOrSmJIXiwJBECAwEAAaAAMA0GCSqG
      SIb3DQEBCwUAA4IBAQBJlngjOaElK2jLZlThnuVe7UwZSA61NDeM1oQH8k6S4zeL
      wIbDngpXWEjS0J8r02SYMrYM9BQG5+kC+wu0P/jCjm2lFm1eSIdRZbth0lyNVIxQ
      hdJ9nPajJQeEvQ/hI6uRsacwDuiUiwx4y9qkmeDedjpaTyFh/efqTSzL0BVAwgG5
      m3r4z9PL6tDck10dm56Nfdmz1Kq2e10S2Um4mD2PcJTiQPZazacVt+4sGuXoRSJ9
      LHhFfCslubF1tCV47eTFdlPA2IhOf0qhWRSEaWMsqh33Nqj4AdHnsKHILZlSmwbf
      Nv5cbUGKup7jC4Q4KxNkOaU19rQyZew0dO/SxZfP
      -----END CERTIFICATE REQUEST-----
  status: completed
  timing:
    completed: 2020-03-20 14:15:15 +0000 UTC
    enqueued: 2020-03-20 14:15:07 +0000 UTC
    started: 2020-03-20 14:15:10 +0000 UTC
  unit: vault/0
ubuntu@OrangeBox84:~/fce-demo$

========= Juju 2.7 =========

ubuntu@OrangeBox84:~/fce-demo$ juju status
Model Controller Cloud/Region Version SLA Timestamp
vault foundations-maas maas_cloud/default 2.7.3 unsupported 13:50:38Z

App Version Status Scale Charm Store Rev OS Notes
easyrsa 3.0.1 active 1 easyrsa jujucharms 296 ubuntu
etcd 3.2.10 active 1 etcd jujucharms 496 ubuntu
mysql 5.7.20 active 3 percona-cluster jujucharms 284 ubuntu
vault 1.1.1 active 1 vault jujucharms 36 ubuntu

Unit Workload Agent Machine Public address Ports Message
easyrsa/0* active idle 0/lxd/0 172.27.85.121 Certificate Authority connected.
etcd/0* active idle 0/lxd/1 172.27.85.119 2379/tcp Healthy with 1 known peer
mysql/0* active idle 1/lxd/0 172.27.85.120 3306/tcp Unit is ready
mysql/1 active idle 0/lxd/2 172.27.85.123 3306/tcp Unit is ready
mysql/2 active idle 1/lxd/2 172.27.85.124 3306/tcp Unit is ready
vault/0* active idle 1/lxd/1 172.27.85.122 8200/tcp Unit is ready (active: true, mlock: disabled)

Machine State DNS Inst id Series AZ Message
0 started 172.27.85.117 node01 bionic default Deployed
0/lxd/0 started 172.27.85.121 juju-0790e1-0-lxd-0 bionic default Container started
0/lxd/1 started 172.27.85.119 juju-0790e1-0-lxd-1 bionic default Container started
0/lxd/2 started 172.27.85.123 juju-0790e1-0-lxd-2 bionic default Container started
1 started 172.27.85.118 node02 bionic default Deployed
1/lxd/0 started 172.27.85.120 juju-0790e1-1-lxd-0 bionic default Container started
1/lxd/1 started 172.27.85.122 juju-0790e1-1-lxd-1 bionic default Container started
1/lxd/2 started 172.27.85.124 juju-0790e1-1-lxd-2 bionic default Container started

ubuntu@OrangeBox84:~/fce-demo$ juju run-action vault/leader get-csr --wait
unit-vault-0:
  UnitId: vault/0
  id: "1"
  results:
    Stderr: |
      All snaps up to date.
    Stdout: |
      lxc
      lxc
      active
      active
      lxc
    output: |-
      -----BEGIN CERTIFICATE REQUEST-----
      MIICijCCAXICAQAwRTFDMEEGA1UEAxM6VmF1bHQgSW50ZXJtZWRpYXRlIENlcnRp
      ZmljYXRlIEF1dGhvcml0eSAoY2hhcm0tcGtpLWxvY2FsKTCCASIwDQYJKoZIhvcN
      AQEBBQADggEPADCCAQoCggEBAObGNqSIzTzDH1qGkrFbaXICTvcJlMCXTN3lzG3c
      8ZN+Rf1AGHnKeGRbbcUezqDXShyKBQM6DKh4tmg25x1ZmaKgCW2WVcY5u12bRLav
      WJ1ZxmcQH9r1qyWUSMmx15vdcm5SkOojoD3Q3DbdkQ+/b118uQbJrKzLnyTVeneU
      jvhZZH6MP1SAl8CCy2VHR9stlTYPSuN9eJWWGGo9BP492p/RUqHLRiIP+IqnKs6N
      HxttHg/e5geHGP5vxpzHHpn5OaQ+YDALElVQyGDxXxZMWH98oVL0uj94XVts1Uhl
      yWPwyIjEYXjGHiwgtiuIhqERbTrPTT+GboKTGxDoknU5hCECAwEAAaAAMA0GCSqG
      SIb3DQEBCwUAA4IBAQBYgsSEkuIUqPCs7p6WCtawutZvvFPDhojO7rlZtN4wX98q
      oPRTwjiFo5ngpspbycsuhNJofDe/Slv6q0YIGYixm2IwsYpmOVomEAs0FBFyKRvq
      YlEp8FUblIeooqnL6TYl11rxgYc9sdQfHB8QJ0TPjIeuzSpiDMp3WagdiKstfRlh
      xuhQMx0zzn9e9rXolss+obNgZk4PUk20CZ0Qdp3D1RUo3fQR1TmI+dfTx8ZVDDQO
      Ou2XM5BwQyEdUgBZFXWQIF4GoO1n0nTGxVLI+ZquEE+RksNapoUKER0h18ofpPoy
      oO2WQjt6SCL26GLIZjl9I7HOCQmaIHDTORIlVbeC
      -----END CERTIFICATE REQUEST-----
  status: completed
  timing:
    completed: 2020-03-20 12:12:27 +0000 UTC
    enqueued: 2020-03-20 12:12:18 +0000 UTC
    started: 2020-03-20 12:12:22 +0000 UTC