bug: tailnet coordinator can drop node updates in race condition #7295
Description
Spotted using the logging from #7260
The tailnet coordinator sometimes drops a Node update, causing connections to agents to fail to be established.
TestAgent_EnvironmentVariables.txt
See above logs for detailed sequence.
It's a classic concurrency bug:
- Grab the latest data
- Subscribe to updates
If an update comes in between 1 and 2, we miss it.