cn/r won't proxy
Hello,
with 2.14.0 on Linux I can't propper proxy **cn/r**. Please note that this setup worked for xmr_v7, xmr_v8, xmr_heavy, xmr_heaven. But not now for "r" variant.

When miners with no login and no password are sent to this xmr-rig-proxy 2.14.0 it wouldn't get any accepts, just rejects and ranrom errors (share above target, job not found or others). Ive tried Nicehash (priamry target now) and also two non-nicehash pools (cn/r direct).

I've tried all kind of config variants but no success.
Now Im using:

```
{
    "access-log-file": "/var/log/xmr_proxy_access.log",
    "algo": "cn/r",
    "api": {
        "port": 0,
        "access-token": null,
        "worker-id": null,
        "ipv6": false,
        "restricted": true
    },
    "background": false,
    "bind": [
        "0.0.0.0:8823",
        "0.0.0.0:5523"
    ],
    "mode": "simple",
    "colors": true,
    "donate-level": 0,
    "log-file": "/var/log/xmr_proxy.log",
    "pools": [
        {
            "url": "cryptonightr.eu.nicehash.com:3375",
            "user": "3K4xxxxxxxxxxxxxxxxxxxxxxxxxxxx",
            "pass": "test",
            "keepalive": true,
            "variant": "r",
            "height": "",
            "tls": false,
            "tls-fingerprint": null
        }
    ],
    "retries": 2,
    "retry-pause": 10,
    "syslog": false,
    "verbose": true,
    "workers": "user"
}
```

Ive tried:
```
"algo": "cn/r"
"algo": "cn"
"mode": "simple"
"mode": "nicehash"
"variant": "r"
"variant": ""
"variant": 8
```

... same results. Miners are set to use nicehash, but have none login and password.
When miners are set directly to xmr-proxy WITH login and password (unique worker name), it somehow worked. Its kinda strange. Because proxy rewrites all login and passwords to own one and sends them to nicehash.

Ive tried also 2.14.1 version but with same result. Im not on 2.14.0.
Please note that this setup worked with previous algos quite well. It is strange that now its struggles. Im suspection some bug on proxy side within name rewrites for "r" variant. Turning on debug mode ("d" key) whos some strange utf chars at logins at xml.

Output follows:


```
[xxx xmrig-proxy-2.14.0]# ./cmd-line-start2.sh
 * ABOUT        xmrig-proxy/2.14.0 gcc/5.4.0
 * LIBS         libuv/1.24.1 OpenSSL/1.1.1a microhttpd/0.9.62
 * MODE         simple
 * ALGO         cryptonight/r
 * POOL #1      cryptonightr.eu.nicehash.com:3375 variant r
 * BIND #1      0.0.0.0:8823
 * BIND #2      0.0.0.0:5523
 * COMMANDS     hashrate, connections, verbose, workers
[2019-03-23 09:21:08] #000 use pool cryptonightr.eu.nicehash.com:3375  123.xx.xx.45
[2019-03-23 09:21:08] #000 new job from cryptonightr.eu.nicehash.com:3375 diff 100001 algo cn/r height 1796899
[2019-03-23 09:21:08] #001 use pool cryptonightr.eu.nicehash.com:3375  123.xx.xx.45
[2019-03-23 09:21:08] #001 new job from cryptonightr.eu.nicehash.com:3375 diff 100001 algo cn/r height 1796899
[2019-03-23 09:21:10] #002 use pool cryptonightr.eu.nicehash.com:3375  123.xx.xx.45
[2019-03-23 09:21:10] #002 new job from cryptonightr.eu.nicehash.com:3375 diff 100001 algo cn/r height 1796899
[2019-03-23 09:21:10] #003 use pool cryptonightr.eu.nicehash.com:3375  123.xx.xx.45
[2019-03-23 09:21:10] #003 new job from cryptonightr.eu.nicehash.com:3375 diff 100001 algo cn/r height 1796899
...
[2019-03-23 09:21:18] #000 rejected (0/1+0) diff 100001 ip 222.xx.xx.22 "Job not found." (41 ms)

[2019-03-23 09:21:31] #018 rejected (0/6+0) diff 100001 ip 222.xx.xx.22 "Share above target." (151 ms)
[2019-03-23 09:21:31] #015 rejected (0/7+0) diff 100001 ip 222.xx.xx.22 "Share above target." (145 ms)
[2019-03-23 09:22:17] Ctrl+C received, exiting


```