09c6699900 [qa] Handle disconnect_node race (Suhas Daftuar)
Pull request description:
Several tests call disconnect_nodes() on each node-pair in rapid
succession, resulting in a race condition if a node disconnects a peer
in-between the calculation of the nodeid's to disconnect and the
invocation of the disconnectnode rpc call. Handle this.
Tree-SHA512: 3078cea0006fcb507c812004a777c505eb1e9dda7c6df12dbbe72395a73ff6f6760f597b6492054f5487b34534417ddef5fbad30553c135c288c4b7cfce79223