Concurrency limits
Use bb concurrency-limit status --json to inspect current limits.
bb concurrency-limit global [unlimited|<limit>] [--json]
bb concurrency-limit host <host-id> [auto|<limit>] [--json]
Automatic host limits allow one thread per available processor. Resolve the host
with bb machine list before changing a host limit. Omit the value to inspect it;
change limits only for the requested scope and verify the resulting status.