xmrig-proxy 2.6.3 crashes on no DNS/no internet
``` * VERSIONS    xmrig-proxy/2.6.3 libuv/1.9.1 gcc/5.4.0
 * MODE        simple
 * ALGO        cryptonight
 * POOL #1     cryptonightv7.eu.nicehash.com:3363 variant 1
 * POOL #2     cryptonightv7.hk.nicehash.com:3363 variant 1
 * BIND #1     192.168.30.5:3333
 * COMMANDS    hashrate, connections, verbose, workers
[skipped]
[2018-06-24 23:59:36] 3.33 kH/s, shares: 4272/3 +2, upstreams: 2, miners: 2 (max 2) +0/-0
[2018-06-25 00:00:36] 10.00 kH/s, shares: 4278/3 +6, upstreams: 2, miners: 2 (max 2) +0/-0
[2018-06-25 00:01:36] 0.00 kH/s, shares: 4278/3 +0, upstreams: 1, miners: 1 (max 2) +0/-1
[2018-06-25 00:02:16] [cryptonightv7.eu.nicehash.com:3363] DNS error: "temporary failure"
xmrig-proxy: src/unix/getaddrinfo.c:121: uv__getaddrinfo_done: Assertion `0' failed.
./xm.nh: line 1: 30024 Aborted                 (core dumped) ~/compile/proxy/build/xmrig-proxy -o cryptonightv7.eu.nicehash.com:3363 -u skipskip -o cryptonightv7.hk.nicehash.com:3363 -u skipskip -p x --bind 192.168.30.5:3333 --mode simple --variant -1 -l ~/compile/xm-nh.log
```

It could work flawlessly for weeks, then we have an issue somewhere inside the LAN and boom.
Full command line is at last line of the log above. Same issue with 2.6.2 and 2.5x.
Ubuntu 16.04.4 LTS, x86_64, kernel 4.4.0-127-generic.
There is no core despite it says "core dumped".