test: add test case for issue 13268
test: add test case for issue 13268

See https://go-review.googlesource.com/#/c/17047/ for the bug fix.

Change-Id: Id5b0a37439d0f8f1e668f7c2ac84335b37f3a300
Reviewed-on: https://go-review.googlesource.com/17177
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
Run-TryBot: Robert Griesemer <a6752097faebf1f02d80107d77a9be009089afe3@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

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