net/http: testClientHead now in http2 mode
net/http: testClientHead now in http2 mode

Change-Id: I21317e3f60502759efc026cdfdb0b1d5f411cae9
Reviewed-on: https://go-review.googlesource.com/17521
Run-TryBot: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

josharian/go,vanloswang/go,momchil-velikov/go,ImJasonH/go,binarycrusader/go,miolini/go,CAFxX/go,cyberroadie/go,cloudflare/go,odeke-em/go,derekmarcotte/go,binarycrusader/go,kim-racktop/go,deft-code/go,CAFxX/go,sndnvaps/go,4ad/go,vsekhar/elastic-go,golang/go,odeke-em/go,momchil-velikov/go,miolini/go,Endika/go,Samurais/go,miolini/go,goodlang/good,akutz/go,polyverse-security/go,kim-racktop/go,josharian/go,CAFxX/go,ImJasonH/go,cyberroadie/go,miolini/go,polyverse-security/go,Endika/go,momchil-velikov/go,cloudflare/go,deft-code/go,mwhudson/go,linux-on-ibm-z/go,golang/go,suncycheng/go,linux-on-ibm-z/go,CAFxX/go,vanloswang/go,Endika/go,nawawi/go,akutz/go,momchil-velikov/go,derekmarcotte/go,theif519/go,odeke-em/go,theif519/go,momchil-velikov/go,roth1002/go,goodlang/good,fjballest/golang,suncycheng/go,roth1002/go,vsekhar/elastic-go,linux-on-ibm-z/go,polyverse-security/go,fjballest/golang,kim-racktop/go,ganboing/go-esx,goodlang/good,odeke-em/go,polyverse-security/go,mwhudson/go,Endika/go,akutz/go,goodlang/good,roth1002/go,Cofyc/go,ImJasonH/go,josharian/go,josharian/go,josharian/go,Cofyc/go,cyberroadie/go,mwhudson/go,theif519/go,vsekhar/elastic-go,ganboing/go-esx,ImJasonH/go,kim-racktop/go,vsekhar/elastic-go,odeke-em/go,Cofyc/go,linux-on-ibm-z/go,vanloswang/go,golang/go,deft-code/go,cloudflare/go,ganboing/go-esx,ganboing/go-esx,deft-code/go,binarycrusader/go,nawawi/go,roth1002/go,ImJasonH/go,Cofyc/go,miolini/go,codestation/go,mwhudson/go,Samurais/go,binarycrusader/go,kim-racktop/go,theif519/go,codestation/go,linux-on-ibm-z/go,Endika/go,deft-code/go,suncycheng/go,fjballest/golang,cyberroadie/go,4ad/go,akutz/go,derekmarcotte/go,vanloswang/go,deft-code/go,4ad/go,mwhudson/go,vanloswang/go,ImJasonH/go,goodlang/good,odeke-em/go,fjballest/golang,suncycheng/go,mwhudson/go,cloudflare/go,fjballest/golang,sndnvaps/go,ganboing/go-esx,goodlang/good,suncycheng/go,goodlang/good,codestation/go,cyberroadie/go,ganboing/go-esx,kim-racktop/go,miolini/go,roth1002/go,ganboing/go-esx,derekmarcotte/go,momchil-velikov/go,linux-on-ibm-z/go,sndnvaps/go,golang/go,cloudflare/go,4ad/go,Cofyc/go,nawawi/go,Endika/go,deft-code/go,akutz/go,fjballest/golang,CAFxX/go,odeke-em/go,cyberroadie/go,Cofyc/go,sndnvaps/go,mwhudson/go,linux-on-ibm-z/go,momchil-velikov/go,suncycheng/go,akutz/go,theif519/go,cyberroadie/go,codestation/go,theif519/go,cloudflare/go,nawawi/go,Samurais/go,suncycheng/go,akutz/go,golang/go,codestation/go,binarycrusader/go,josharian/go,ImJasonH/go,binarycrusader/go,sndnvaps/go,derekmarcotte/go,nawawi/go,derekmarcotte/go,binarycrusader/go,Cofyc/go,CAFxX/go,theif519/go,vanloswang/go,vanloswang/go,odeke-em/go,goodlang/good,CAFxX/go,fjballest/golang,sndnvaps/go,theif519/go,kim-racktop/go,momchil-velikov/go,4ad/go,miolini/go,4ad/go,cloudflare/go,sndnvaps/go,suncycheng/go,Endika/go,josharian/go,codestation/go,linux-on-ibm-z/go,cloudflare/go,CAFxX/go,codestation/go,roth1002/go,vsekhar/elastic-go,codestation/go,4ad/go,Samurais/go,Samurais/go,sndnvaps/go,Endika/go,roth1002/go,fjballest/golang,polyverse-security/go,deft-code/go,polyverse-security/go,golang/go,akutz/go,miolini/go,derekmarcotte/go,Samurais/go,polyverse-security/go,Samurais/go,golang/go,vsekhar/elastic-go,binarycrusader/go,ganboing/go-esx,cyberroadie/go,roth1002/go,mwhudson/go,vsekhar/elastic-go,nawawi/go,polyverse-security/go,derekmarcotte/go,josharian/go,ImJasonH/go,nawawi/go,vsekhar/elastic-go,golang/go,4ad/go,vanloswang/go,Samurais/go,kim-racktop/go,nawawi/go,Cofyc/go,christopher-henderson/Go