Cleaning fails if conductor thread can not be started

[Yuriy Zveryanskyy]

We ignore exception.NoFreeConductorWorker in the agent driver and waiting for the next heartbeat, but 'resume' event already processed in the continue_node_clean() conductor's method before spawning a thread. As result cleaning fails even if next heartbeat can execute thread via conductor.

[Joanna Taryma (jtaryma)]

Pass for exception.NoFreeConductorWorker doesn't change anything, because it is never raised in agent driver.
NoFreeConductorWorker is raised in conductor's continue_node_clean, which is called via RPC cast. That means, even if continue_node_clean raises any exception, it won't get propagated to agent driver due to async communication.

I think exception handling code should be removed as it's misleading.

Going forward - currently there is no mean for the agent to know about failure in continue_node_clean. Similar problems may be found in other functions that communicate via RPC. Either all of that should be handled on conductor side, or we have to think about the way to inform about failures

[Dmitry Tantsur (divius)]

Removing assignee after more than a year of inactivity