if err != nil {
			retErr = err
			if keepCoverage != nil {
				// Now that we've found a crash, that's more important than any
				// minimization of interesting inputs that was being done. Clear out
				// keepCoverage to only minimize the crash going forward.
				keepCoverage = nil
			}
			return true
		}
		// Minimization should preserve coverage bits.

	// A zero timeout means no limit.
	timeout time.Duration

	// keepCoverage is a set of coverage bits that entry found that were not in
	// the coordinator's combined set. When minimizing, the worker should find an
	// input that preserves at least one of these bits. keepCoverage is nil for
	// crashing inputs.
	keepCoverage []byte
}

// coordinator holds channels that workers can use to communicate with