KeepConnectedToMaster ran on context.Background(), so once RunShell
returned — including the new connect-timeout early return — the
reconnect goroutine kept dialing forever, and repeated RunShell calls
accumulated one each. Give it its own cancellable context, separate
from connectCtx whose deadline must not cut reconnects under a live
shell.
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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>