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

$ go version
go version go1.16rc1 freebsd/amd64

Does this issue reproduce with the latest release?

No idea.

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

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/usr/home0/bakul/.cache/go-build"
GOENV="/usr/home0/bakul/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="freebsd"
GOINSECURE=""
GOMODCACHE="/usr/home0/bakul/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="freebsd"
GOPATH="/usr/home0/bakul/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/freebsd_amd64"
GOVCS=""
GOVERSION="go1.16rc1"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/tmp/go/src/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3525808295=/tmp/go-build -gno-record-gcc-switches"

What did you do?

$ git clone https://go.googlesource.com/dl
$ cd dl/go1.16rc1
$ go run main.go download
$ sudo mv ~/sdk/go1.16rc1 /usr/local/go
$ cd /usr/local/go/src
$ ./all.bash

What did you expect to see?

all tests to pass

What did you see instead?

ok      net     160.991s

The above test should take may be 2 seconds

2021/01/29 00:20:35 httptest.Server blocked in Close after 5 seconds, waiting for connections:
  *net.TCPConn 0xc00071e168 127.0.0.1:46910 in state active
--- FAIL: TestTransportCloseResponseBody (79.37s)
    transport_test.go:2669: too long waiting for write error
2021/01/29 00:21:45 httptest.Server blocked in Close after 5 seconds, waiting for connections:
  *net.TCPConn 0xc0002f4020 127.0.0.1:48478 in state active
2021/01/29 00:21:45 httptest.Server blocked in Close after 5 seconds, waiting for connections:
  *net.TCPConn 0xc00085e048 127.0.0.1:48501 in state active
2021/01/29 00:21:45 httptest.Server blocked in Close after 5 seconds, waiting for connections:
  *net.TCPConn 0xc0003a00d0 127.0.0.1:48504 in state active
2021/01/29 00:21:45 httptest.Server blocked in Close after 5 seconds, waiting for connections:
  *net.TCPConn 0xc000410038 127.0.0.1:48506 in state active
  *net.TCPConn 0xc000466038 127.0.0.1:48528 in state active
FAIL
FAIL    net/http        201.785s

And..

ok      os/exec 484.477s

This too should take a couple seconds or so.

ok      cmd/vet 26.172s
FAIL

No further tests were run after this