net/http: context isn't canceled on client disconnection

[utrack]

What version of Go are you using (go version)?

go version go1.7.4 linux/amd64

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/u/go"
GORACE=""
GOROOT="/usr/lib/go"
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build348831087=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

Arch Linux

What did you do?

Stumbled upon it on failing tests. Here's a snippet:
https://play.golang.org/p/v4ij4Elrqa

What did you expect to see?

Get http://127.0.0.1:2/: context deadline exceeded
true

Works like this on latest (go 1.8.*)

What did you see instead?

Get http://127.0.0.1:44773/: net/http: request canceled
false

This test is kinda hacky b/c .Shutdown() and .Close() aren't there on Go 1.7.
The point is: r.Context() is never canceled on server's side once client disconnects.

[bradfitz]

Correct. This was implemented in Go 1.8.