`dial attempt failed: EOF` when `go test` in macOS

Nobody has claimed this yet.

I run the command in both macOS High Sierra(10.13.6) and ubuntu 16.04 and get this issue only in my macOS. I removed the entire `$GOPATH/src`, and performed `go get` again. This issue is still there.

```
$ gx-go rw
$ go test -v
...
=== RUN TestSparseGossipsub
--- PASS: TestSparseGossipsub (3.00s)
=== RUN TestDenseGossipsub
--- FAIL: TestDenseGossipsub (0.91s)
floodsub_test.go:54: dial attempt failed: --> dial attempt failed: EOF
=== RUN TestGossipsubFanout
--- FAIL: TestGossipsubFanout (1.01s)
floodsub_test.go:54: dial attempt failed: --> dial attempt failed: EOF
=== RUN TestGossipsubFanoutMaintenance
--- FAIL: TestGossipsubFanoutMaintenance (0.95s)
floodsub_test.go:54: dial attempt failed: --> dial attempt failed: EOF
=== RUN TestGossipsubFanoutExpiry
--- PASS: TestGossipsubFanoutExpiry (4.53s)
=== RUN TestGossipsubGossip
--- FAIL: TestGossipsubGossip (1.02s)
floodsub_test.go:54: dial attempt failed: --> dial attempt failed: EOF
=== RUN TestGossipsubGossipPiggyback
--- FAIL: TestGossipsubGossipPiggyback (1.06s)
floodsub_test.go:54: dial attempt failed: --> dial attempt failed: EOF
...
```
After debugging for a while, I still don't have any idea about this issue. I will really appreciate if there is any direction to solve it.

Reproduce the failure with `go test -v` on macOS, then inspect `floodsub_test.go:54` and the failing `TestDenseGossipsub`, `TestGossipsubFanout`, and related tests. Compare the macOS and Ubuntu test environments and trace the reported dial attempts; done means the affected tests pass reliably on macOS or the platform-specific cause is clearly documented.

Written by the indexing model from the issue text.