oadm diagnostics NetworkCheck fails.

Issue

• oadm diagnostics NetworkCheck fails with error.

[...]

ERROR: [DSvcNet1010 from diagnostic CheckServiceNetwork@openshift/origin/pkg/diagnostics/networkpod/service.go:189]
       Connectivity from pod "network-diag-xxx/network-diag-test-pod-nhmj2" to service "network-diag-xxx/network-diag-test-service-4czhz" failed. Error: exit status 124, Out:

ERROR: [DSvcNet1010 from diagnostic CheckServiceNetwork@openshift/origin/pkg/diagnostics/networkpod/service.go:189]
       Connectivity from pod "network-diag-xxx/network-diag-test-pod-6dfxj" to service "network-diag-xxx/network-diag-test-service-4czhz" failed. Error: exit status 1, Out: bash: connect: Connection refused
       bash: /dev/tcp/172.X.X.X/9876: Connection refused

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