+5931. [bug] Fix DiG query error handling robustness in NSSEARCH
+ mode by making sure that udp_ready(), tcp_connected(),
+ and send_done() callbacks start the next query in chain
+ even if there is some kind of error with the previous
+ query. [GL #3419]
+
5930. [bug] Fix DiG query retry and fail-over bug in UDP mode.
Also simplify the overall retry and fail-over logic to
make it behave predictably, and always respect the