Unclosed Span in ribbon client

[dsyer]

This one is hard to reproduce I think, but @joshlong had a sample where there were WARN logs about uncloseable spans from a Ribbon client that couldn't resolve its server. It was using Feign as well.

[marcingrzejszczak]

Josh can you provide these steps to reproduce it?

[dsyer]

I think I did it. If I use Feign and Ribbon/Hystrix and don't define a server list I can break the ribbon sample in Sleuth.

[dsyer]

Commit 84f4d37 adds a sample that fails (e.g. run it and curl localhost:3383/).

[dsyer]

I have a test that fails and I can fix it, but it won't run in a suite because of some stale state from one of the other tests. Needs more work.