Concurrent calls to LocalBackend.setWgengineStatus
could result in some of the status updates being dropped.
This was exacerbated by 92077ae78c,
which increases the probability of concurrent status updates,
causing test failures (tailscale/corp#2579).
It's going to take a bit of work to fix this test.
The ipnlocal state machine is difficult to reason about,
particularly in the face of concurrency.
We could fix the test trivially by throwing a new mutex around
setWgengineStatus to serialize calls to it,
but I'd like to at least try to do better than cosmetics.
In the meantime, commit the test.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
b681edc572