go: testing: test failes if leaving files without write permission in T.TempDir

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

$ go version
go version go1.15 darwin/amd64

Does this issue reproduce with the latest release?

yes

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

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/tikuta/Library/Caches/go-build"
GOENV="/Users/tikuta/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/tikuta/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/tikuta/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/tikuta/homebrew/Cellar/go/1.15/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/tikuta/homebrew/Cellar/go/1.15/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
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=/var/folders/jz/z42xl9mx2d576zq1q21hlggc00bk9x/T/go-build114835528=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I wrote a test leaving a file without write permission.

package test

import (
        "io/ioutil"
        "os"
        "path/filepath"
        "testing"
)

func TestNoDir(t *testing.T) {
        dir := t.TempDir()
        empty := filepath.Join(dir, "empty")

        if err := os.MkdirAll(filepath.Dir(empty), 0300); err != nil {
                t.Errorf("%v", err)
        }

        if err := ioutil.WriteFile(empty, nil, 0444); err != nil {
                t.Errorf("%v", err)
        }
}

func TestDir(t *testing.T) {
        dir := t.TempDir()
        empty := filepath.Join(dir, "a", "empty")

        if err := os.MkdirAll(filepath.Dir(empty), 0300); err != nil {
                t.Errorf("%v", err)
        }

        if err := ioutil.WriteFile(empty, nil, 0444); err != nil {
                t.Errorf("%v", err)
        }
}

What did you expect to see?

Both test passed.

What did you see instead?

Only TestNoDir passed.

$ go test -v go_test.go
=== RUN   TestNoDir
--- PASS: TestNoDir (0.00s)
=== RUN   TestDir
    testing.go:894: TempDir RemoveAll cleanup: openfdat /var/folders/jz/z42xl9mx2d576zq1q21hlggc00bk9x/T/TestDir492614072/001/a: permission denied
--- FAIL: TestDir (0.00s)
FAIL
FAIL    command-line-arguments  0.115s
FAIL