use blocking mode pre-go1.11

syscalls_darwin_legacy.go

@@ -0,0 +1,10 @@
+// +build darwin,!go1.11
+
+package water
+
+func setNonBlock(fd int) error {
+	// There's a but pre-go1.11 that causes 'resource temporarily unavailable'
+	// error in non-blocking mode. So just skip it here. Close() won't be able
+	// to unblock a pending read, but that's better than being broken.
+	return nil
+}