Comment 5 for bug 1577632

I've faced with the same problem and found that root cause deadlock in paramiko.
Here is gdb trace from out CI http://paste.openstack.org/raw/560777/

Last tempest test "tempest.scenario.test_server_basic_ops.TestServerBasicOps.test_server_basic_ops"
calls remote ssh exec_command which uses paramiko recv_exit_status method that hangs and keep waiting event from another thread (which is died and never happened) forever.
Seems, it should have some timeout for receive.

Also, I found warnings in paramiko docs about method "recv_exit_status"
http://docs.paramiko.org/en/2.0/api/channel.html#paramiko.channel.Channel.recv_exit_status
http://docs.paramiko.org/en/2.0/api/channel.html#paramiko.channel.Channel.exit_status_ready

and unresolved issues with the
https://github.com/paramiko/paramiko/search?q=recv_exit_status&type=Issues&utf8=%E2%9C%93

Do we have this issue on tempest gates ?