'ping' command seems to fail with Parity clients

```shell
ubp52 ~/go/src/github.com/etclabscore/dp2p dev-scripts2 %
$ while read -r c en; do echo "$c $en" && ./dp ping -t 1000 "$en"; done udp=0 tcp=0
TRACE[03-28|19:28:48.785] >> PING/v4 id=04a037eabb45f18c addr=178.128.55.119:30303 err=nil
RPC timeout
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://0daae2a30f2c73b0b257746587136efb8e3479496f7ea1e943eeb9a663b72dd04582f699f7010ee02c57fc45d1f09568c20a9050ff937f9139e2973ddd98b87b@159.89.169.103:30303
INFO [03-28|19:28:49.809] New local node record seq=1 id=9f72f82b8cc1add8 ip= udp=0 tcp=0
TRACE[03-28|19:28:49.809] >> PING/v4 id=22ec854117125934 addr=159.89.169.103:30303 err=nil
RPC timeout
Geth/v5.5.1-8a3bc2d/linux/go1.9.7 enode://7e2995638c8a3c7eb721e1005edc0ff046060561fc5903733b62e1b22a224dc28134331111f5c89661edc7e217dd528953c17071ecb6a46f4196ec027a877ea3@35.192.216.216:30306
INFO [03-28|19:28:50.836] New local node record seq=1 id=48239749a6eb0925 ip= udp=0 tcp=0
TRACE[03-28|19:28:50.836] >> PING/v4 id=45c950527320975b addr=35.192.216.216:30306 err=nil
RPC timeout
Parity-Ethereum/EthereumClassicSOLO/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://e212927fecf112d705b56bc1dd3f951b7416a5be56748d22b609771bde849452a134f59222cc9d1c2908461b4722bb4a904e582250796474bb9477a56baa47d3@104.248.230.186:40304
INFO [03-28|19:28:51.857] New local node record seq=1 id=c6e0d490a85db476 ip= udp=0 tcp=0
TRACE[03-28|19:28:51.858] >> PING/v4 id=6e25686e9bd026a4 addr=104.248.230.186:40304 err=nil
RPC timeout
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://3fe9705a02487baea45c1ffebfa4d84819f5f1e68a0dbc18031553242a6a08e39499b61e361a52c2a92f9553efd63763f6fdd34692be0d4ba6823bb2fc346009@178.62.238.75:30303
INFO [03-28|19:28:52.897] New local node record seq=1 id=a76458a3486b4392 ip= udp=0 tcp=0
TRACE[03-28|19:28:52.897] >> PING/v4 id=9359cec51ae10cdb addr=178.62.238.75:30303 err=nil
RPC timeout
Geth/v5.5.1/linux/go1.9.7 enode://0b307df337d46b45147756780e69cda35b1be6d28996a9f95b650b314156f9072360463468e914c5ce2028cd38ca156bf094fdbdabb2e42418a373f81f7f1396@212.32.247.132:30313
INFO [03-28|19:28:53.919] New local node record seq=1 id=f601bc5831ef2419 ip= udp=0 tcp=0
TRACE[03-28|19:28:53.919] >> PING/v4 id=c2ff322927d1de85 addr=212.32.247.132:30313 err=nil
pong 354.32073ms
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://83b33409349ffa25e150555f7b4f8deebc68f3d34d782129dc3c8ba07b880c209310a4191e1725f2f6bef59bce9452d821111eaa786deab08a7e6551fca41f4f@206.189.68.191:30303
INFO [03-28|19:28:54.296] New local node record seq=1 id=45319b62a6b557ec ip= udp=0 tcp=0
TRACE[03-28|19:28:54.296] >> PING/v4 id=d4731bcf672459cc addr=206.189.68.191:30303 err=nil
RPC timeout
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://c071d96b0c0f13006feae3977fb1b3c2f62caedf643df9a3655bc1b60f777f05e69a4e58bf3547bb299210092764c56df1e08380e91265baa845dca8bc0a71da@68.183.99.5:30303
INFO [03-28|19:28:55.317] New local node record seq=1 id=ce2e3a8fce0ccdff ip= udp=0 tcp=0
TRACE[03-28|19:28:55.317] >> PING/v4 id=f5fb164a5c76dbb5 addr=68.183.99.5:30303 err=nil
RPC timeout
ubp52 ~/go/src/github.com/etclabscore/dp2p dev-scripts2 %
$ cat test_parity_nodes.txt
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://50808461dd73b3d70537e4c1e5fafd1132b3a90f998399af9205f8889987d62096d4e853813562dd43e7270a71c9d9d4e4dd73a534fdb22fbac98c389c1a7362@178.128.55.119:30303
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://0daae2a30f2c73b0b257746587136efb8e3479496f7ea1e943eeb9a663b72dd04582f699f7010ee02c57fc45d1f09568c20a9050ff937f9139e2973ddd98b87b@159.89.169.103:30303
Geth/v5.5.1-8a3bc2d/linux/go1.9.7 enode://7e2995638c8a3c7eb721e1005edc0ff046060561fc5903733b62e1b22a224dc28134331111f5c89661edc7e217dd528953c17071ecb6a46f4196ec027a877ea3@35.192.216.216:30306
Parity-Ethereum/EthereumClassicSOLO/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://e212927fecf112d705b56bc1dd3f951b7416a5be56748d22b609771bde849452a134f59222cc9d1c2908461b4722bb4a904e582250796474bb9477a56baa47d3@104.248.230.186:40304
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://3fe9705a02487baea45c1ffebfa4d84819f5f1e68a0dbc18031553242a6a08e39499b61e361a52c2a92f9553efd63763f6fdd34692be0d4ba6823bb2fc346009@178.62.238.75:30303
Geth/v5.5.1/linux/go1.9.7 enode://0b307df337d46b45147756780e69cda35b1be6d28996a9f95b650b314156f9072360463468e914c5ce2028cd38ca156bf094fdbdabb2e42418a373f81f7f1396@212.32.247.132:30313
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://83b33409349ffa25e150555f7b4f8deebc68f3d34d782129dc3c8ba07b880c209310a4191e1725f2f6bef59bce9452d821111eaa786deab08a7e6551fca41f4f@206.189.68.191:30303
Parity-Ethereum/v2.2.10-stable-7b1d3e1-20190213/x86_64-linux-gnu/rustc1.32.0 enode://c071d96b0c0f13006feae3977fb1b3c2f62caedf643df9a3655bc1b60f777f05e69a4e58bf3547bb299210092764c56df1e08380e91265baa845dca8bc0a71da@68.183.99.5:30303
```

and during analysis of https://github.com/etclabscore/enodes i'm finding that "trimming" enodes list based on successful `dp2p` ping commands gives lists of about 7000 enodes, but with no reported Parity clients. despite expectations for Parity to have about 50% market share.