v1.90.9-sunos

Commits

• 6bc07d3: util/eventbus: add tests for a subscriber trying to acquire the same mutex as a publisher (Nick Khyl) #18040
• f2100e2: util/eventbus: add tests for a subscriber publishing events (Nick Khyl) #18040
• f58cbff: util/eventbus: use unbounded event queues for DeliveredEvents in subscribers (Nick Khyl) #18040
• d7cf0cf: wgengine/userspace: run link change subscribers in eventqueue (tailscale#18024) (Claus Lensbøl) #18054
• 66826a4: VERSION.txt: this is v1.90.9 (Nick Khyl)
• ef1aca7: Merge tag 'v1.90.9' into sunos-1.90 (Nahum Shalman)