This changes the behavior to prevent locking a node that does not match
the requested pool. Currently using a pool locks a node in that pool if
there is one ready, as expected. If there is not one ready from the
pool but there is any other node ready, it will lock a node outside the
pool, not expected and breaking behavior. Also update to handle PyYAML 6.0.0
Change-Id: I285256037e16f94c79cc7d813235460b4032393d