sergey-safarov created an issue (kamailio/kamailio#4180)

### Description

I have installed two `rtpengine` instances and want to use them as an `active backup`. I want to use `backup` only when `active` is unavailable. Closest settings for this rtpengine node `weight` and want to use settings like ``` MariaDB [kamailio]> select * from rtpengine; +----+-------+---------------------------------+--------+----------+---------------------+ | id | setid | url | weight | disabled | stamp | +----+-------+---------------------------------+--------+----------+---------------------+ | 1 | 0 | udp6:[2005:84c0:bf:11::20]:2223 | 1 | 0 | 1900-01-01 00:00:01 | | 2 | 0 | udp6:[2005:84c0:bf:11::21]:2223 | 0 | 0 | 1900-01-01 00:00:01 | +----+-------+---------------------------------+--------+----------+---------------------+ ``` But in case `weight=0` node is not selected and handled as disabled. It will be fine do not use rtpengine nodes with `weight=0` when other rtpengine with `weight!=0` are available. But if no other nodes are available, use `weight=0` nodes as last resort.

### Expected behavior Do not use rtpengine nodes with `weight=0` when other rtpengine with `weight!=0` are available. But if no other nodes are available, use `weight=0` nodes as last resort.

#### Actual observed behavior The node is not selected and handled as disabled when `weight=0`.

#### Log Messages

``` rtpengine [rtpengine.c:3430]: rtpp_test(): rtpengine instance udp6:[2005:84c0:bf:11::21]:2223 found, support for it enabled rtpengine [rtpengine.c:3883]: select_rtpp_node(): rtpengine failed to select new for calllen=27 callid=1-10824@2005:84c0:bf:11::22 rtpengine [rtpengine.c:3183]: rtpp_function_call(): no available proxies ```