Fix crashing http server when callback do not reply in place from *gencb* This is the second hunk of the first patch 5ff8eb26371c4dc56f384b2de35bea2d87814779 ("Fix crashing http server when callback do not reply in place") Fixes: #567 (cherry picked from commit 306747e51c1f0de679a3b165b9429418c89f8d6a)