We're seeing crashes in 15-dev17 that look to be caused by reqirep, reqrep, or reqdel. I haven't make an exhaustive list. Currently we're just seeing them on the devel version from homebrew which is 1.5-dev17. I don't see them on the version provided by ppa:nilya/haproxy-1.5 which is 1.5-dev12.
I'll see if I can reproduce the problem on Linux with the latest version. Nik Everett