On HEAD as of 16DEC2016 (102b66b9730780289ef71fa1ee33214cbcbcdde2)
When in Forward proxy mode, connecting to an HTTPS site, where the destination site responds with TCP RESET, Traffic Server will restart due to Sig 11: Segmentation fault.
If the upstream site instead silently drops the response, ATS will successfully proceed with 502 (Tunnel Connection Failed).
No proxy chaining involved, direct: client -> ATS -> destination.
Test machine: Debian Jessie (8.6) x86_64
To replicate, make an HTTPS request - via ATS in forward-proxy-mode - to a local (non-firewalled) server, with nothing running on TCP/443.
Watch manager.log for near immediate "[LocalManager::pollMgmtProcessServer] Server Process terminated due to Sig 11: Segmentation fault" followed by "[Alarms::signalAlarm] Server Process was reset"
The issue was introduced in c1ac5f8bf87fd4bc3a8e06507219970d83965acd