Revert "Don't set header to nil on HeaderHash#include?"
Revert "Don't set header to nil on HeaderHash#include?"

The change is a bit messy.

This reverts commit f6f3c60938ea3b08f3292a2480e6753c293584e5.

shaneog/rack,wildjcrt/rack,gioele/rack,laplaceliu/rack,deepj/rack,Codeman655/rack,trexnix/rack,eavgerinos/rack,davydovanton/rack,Eric-Guo/rack,ktheory/rack,Comcast/rack,keithduncan/rack,sigmavirus24/rack,eins78/rack,ganmacs/rack,gfvcastro/rack,trexnix/rack,shaneog/rack,keepcosmos/rack,Comcast/rack,AMekss/rack,evanphx/rack,supzann3/rack,tylergannon/rack,davidcelis/rack,rwz/rack,tylergannon/rack,jeremyf/rack,keepcosmos/rack,zjsxwc/rack,eavgerinos/rack,maclover7/rack,ganmacs/rack,ngpestelos/rack,stepri/rack,travis-repos/rack,Eric-Guo/rack,trexnix/rack,tricknotes/rack,liamseanbrady/rack,akihiro17/rack,ngpestelos/rack,jhodder/rack,gfvcastro/rack,rwz/rack,wildjcrt/rack,imtayadeway/rack,evanphx/rack,sigmavirus24/rack,rkh/rack,arronmabrey/rack,jeremyf/rack,rkh/rack,Codeman655/rack,ktheory/rack,laplaceliu/rack,krainboltgreene/lack,Codeman655/rack,getaroom/rack,joevandyk/rack,nmk/rack,chneukirchen/rack,davidcelis/rack,keithduncan/rack,tricknotes/rack,stepri/rack,zjsxwc/rack,gioele/rack,liamseanbrady/rack,getaroom/rack,keepcosmos/rack,fabianrbz/rack,akihiro17/rack,ganmacs/rack,chneukirchen/rack,gfvcastro/rack,evanphx/rack,fabianrbz/rack,arronmabrey/rack,imtayadeway/rack,maclover7/rack,AMekss/rack,Comcast/rack,stepri/rack,laplaceliu/rack,zjsxwc/rack,Eric-Guo/rack,sigmavirus24/rack,nmk/rack,supzann3/rack,AMekss/rack,wjordan/rack,nmk/rack,jackxxu/rack,arronmabrey/rack,maclover7/rack,eavgerinos/rack,deepj/rack,ngpestelos/rack,supzann3/rack,eins78/rack,liamseanbrady/rack,gioele/rack,keithduncan/rack,rwz/rack,eins78/rack,getaroom/rack,chneukirchen/rack,shaneog/rack,paulrogers/rack,davydovanton/rack,deepj/rack,davydovanton/rack,jackxxu/rack,lgierth/rack,tylergannon/rack,wjordan/rack,jackxxu/rack,fabianrbz/rack,imtayadeway/rack,davidcelis/rack,jeremyf/rack,wjordan/rack,wildjcrt/rack,akihiro17/rack