• Make the MagicDNS virtual IP respond to pings (#849)
• Fix failure to update internal state when node keys change (#1391)
• Skip tests that require IPv6 if IPv6 is unavailable (#1292)
• Record whether Tailscale was installed via Chocolatey on Windows.
• Make linux router try harder to continue when encountering errors.
• Add more internal health reporting to the network engine.
• Do PCP availability probing without side-effects, to reduce logspam in home routers.
• Monitor for IPv6 address/route changes on linux.