Repository: go
Issue: cmd/test2json: tests inherit signal.Ignore from test2json
Labels: NeedsInvestigation

### Go version

go version go1.22.1 darwin/arm64

### Output of `go env` in your module/workspace:

```shell
GO111MODULE=''
GOARCH='arm64'
GOBIN=''
GOCACHE='/Users/spike/Library/Caches/go-build'
GOENV='/Users/spike/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/spike/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/spike/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/opt/homebrew/Cellar/go/1.22.1/libexec'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/opt/homebrew/Cellar/go/1.22.1/libexec/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.22.1'
GCCGO='gccgo'
AR='ar'
CC='cc'
CXX='c++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/53/zffdtv3x7lg_pyhrk85p7_nw0000gn/T/go-build3395173330=/tmp/go-build -gno-record-gcc-switches -fno-common'
```


### What did you do?

I have noticed this behavior since upgrading to macOS 14.4.  I don't believe it was present in macOS 14.2

If I have a test case that starts a process and then sends a `SIGINT` to it, the signal is not delivered _if the test case is run via test2json_.  If it is run directly via `go test` or by directly executing a test binary, the signal is delivered.

The following is a minimal testcase that reproduces the behavior:

```
package execsigs

import (
	"errors"
	"os"
	"os/exec"
	"testing"
)

func TestSigInt(t *testing.T) {
	cmd := exec.Command("sleep", "10")
	err := cmd.Start()
	if err != nil {
		t.Fatal(err.Error())
	}
	err = cmd.Process.Signal(os.Interrupt)
	if err != nil {
		t.Fatal(err.Error())
	}
	err = cmd.Wait()
	var exitErr *exec.ExitError
	if !errors.As(err, &exitErr) {
		t.Fail()
	}
}
```

### What did you see happen?

If I run this test via `go test` or create a binary and run it, it passes:

```
spike@Codebook execsigs % go test -v execsigs_test.go
=== RUN   TestSigInt
--- PASS: TestSigInt (0.00s)
PASS
ok  	command-line-arguments	0.833s
spike@Codebook execsigs % go test -c -o test execsigs_test.go
spike@Codebook execsigs % ./test -test.v
=== RUN   TestSigInt
--- PASS: TestSigInt (0.00s)
PASS
```

But if I run via `test2json`, it fails.  The SIGINT is not delivered to `sleep` and so instead of exiting with an error, the test takes 10 seconds and the process exits cleanly.

```
spike@Codebook execsigs % go tool test2json ./test -test.v=test2json
{"Action":"start"}
{"Action":"run","Test":"TestSigInt"}
{"Action":"output","Test":"TestSigInt","Output":"=== RUN   TestSigInt\n"}
{"Action":"output","Test":"TestSigInt","Output":"--- FAIL: TestSigInt (10.01s)\n"}
{"Action":"fail","Test":"TestSigInt"}
{"Action":"output","Output":"FAIL\n"}
{"Action":"fail"}
```

### What did you expect to see?

`test2json` result of the test should be identical to `go test`, i.e. the SIGINT is delivered to the process during the test.

This is pretty annoying because IDEs like GoLand depend on `test2json` to execute go tests under the hood.