requirePrimaryStable in TestHASubnetRouterFailoverDockerDisconnect
Phase 5a (simultaneous cable-pull of both routers) intermittently
caught the primary flipping to the offline r1. Both probe goroutines
mark their target unhealthy back-to-back; SetNodeUnhealthy publishes a
fresh NodeStore snapshot each call, so the intermediate snapshot — r1
unhealthy, r2 still healthy — runs the election with one healthy
candidate left and picks it. The next snapshot then enters the
all-unhealthy preserve-prev path, which preserves the wrong choice.
Collect probe results from the cycle and apply them through a new
NodeStore.UpdateNodes batched op so the election only runs once, with
the cycle's final health state. PolicyChange dispatch moves outside
the wg.Go goroutines and fires once if the primary assignment
actually changed.
de6be71a86