Live migration of instances fails with Failed to connect to remote libvirt URI

Issue

In a brand new OSP11 install, we are seeing live migration failures with following messages:

2017-10-03 16:16:07.379 3631 WARNING nova.compute.manager [req-46bdb8d7-791f-4d57-86ae-29b750b3125e d33baf0e7b7e452e85ba0fb2741bb1b9 dd3aad756c674a7ab41107953f85656f - - -] [instance: 7da7e765-8be1-4333-a1d0-9b875d47d80b] Received unexpected event network-vif-unplugged-dff35986-fce8-4c1a-9c2a-fa5ff178c69c for instance
2017-10-03 16:16:07.640 3631 WARNING nova.compute.manager [req-f0798e2c-c4c3-4b0c-b1b1-5f42fa2d80d6 d33baf0e7b7e452e85ba0fb2741bb1b9 dd3aad756c674a7ab41107953f85656f - - -] [instance: 7da7e765-8be1-4333-a1d0-9b875d47d80b] Received unexpected event network-vif-plugged-dff35986-fce8-4c1a-9c2a-fa5ff178c69c for instance
2017-10-03 16:16:07.731 3631 ERROR nova.virt.libvirt.driver [req-0c3fe0e2-c690-4c8e-865c-68f2c0db2a0d 42527f724579462e9d238165aadc301d f21a6fd109ac43dda826849ea41abffe - - -] [instance: 7da7e765-8be1-4333-a1d0-9b875d47d80b] Live Migration failure: operation failed: Failed to connect to remote libvirt URI qemu+ssh://nova_migration@<hostname>/system?keyfile=/etc/nova/migration/identity: Cannot recv data:
    |------------------------------------------------------------------|
    |   WARNING: Logon attempts are audited. Access and use allowed    |
    |   for authorized purposes only. Violators will be prosecuted.    |
    |------------------------------------------------------------------|

Permission denied, please try again.^M
Permission denied, please try again.^M
Received disconnect from 192.168.101.22 port 22:2: Too many authentication failures^M
Authentication failed.: Connection reset by peer
2017-10-03 16:16:08.090 3631 ERROR nova.virt.libvirt.driver [req-0c3fe0e2-c690-4c8e-865c-68f2c0db2a0d 42527f724579462e9d238165aadc301d f21a6fd109ac43dda826849ea41abffe - - -] [instance: 7da7e765-8be1-4333-a1d0-9b875d47d80b] Migration operation has aborted
2017-10-03 16:16:09.461 3631 WARNING nova.compute.manager [req-1a7a0ab2-0665-40be-a7b4-07edd60bc254 d33baf0e7b7e452e85ba0fb2741bb1b9 dd3aad756c674a7ab41107953f85656f - - -] [instance: 7da7e765-8be1-4333-a1d0-9b875d47d80b] Received unexpected event network-vif-plugged-dff35986-fce8-4c1a-9c2a-fa5ff178c69c for instance