I think I've got it. It's actually a bug in httpcore 4.0-beta2. I've raised https://issues.apache.org/jira/browse/HTTPCORE-170, which has the details.
- Occasionally loosing response for hosted service within ... WALTON Jason
- Re: Occasionally loosing response for hosted servic... Asankha C. Perera
- RE: Occasionally loosing response for hosted se... WALTON Jason
- RE: Occasionally loosing response for hosted servic... Hubert, Eric
- RE: Occasionally loosing response for hosted se... WALTON Jason
- RE: Occasionally loosing response for hoste... WALTON Jason
- RE: Occasionally loosing response for h... WALTON Jason
- Re: Occasionally loosing response ... Asankha C. Perera
- RE: Occasionally loosing respo... WALTON Jason
- Re: Occasionally loosing r... Asankha C. Perera
