fix crash when receiving multiple requests on a single connection
fix crash when receiving multiple requests on a single connection

cwyang/h2o,cwyang/h2o,devnexen/h2o,yannick/h2o,yannick/h2o,h2o/h2o,yannick/h2o,devnexen/h2o,yannick/h2o,h2o/h2o,devnexen/h2o,h2o/h2o,devnexen/h2o,h2o/h2o,devnexen/h2o,cwyang/h2o,yannick/h2o,cwyang/h2o,devnexen/h2o,devnexen/h2o,h2o/h2o,devnexen/h2o,yannick/h2o,h2o/h2o,h2o/h2o,yannick/h2o,cwyang/h2o,devnexen/h2o,cwyang/h2o,h2o/h2o,cwyang/h2o,h2o/h2o,yannick/h2o,cwyang/h2o,yannick/h2o