cmd/go: convert TestIssue11709 to the script framework

Part of converting all tests to script framework to improve
test parallelism.

Updates #36320
Updates #17751

Change-Id: I16fb0910196c96caef6ed380f96010a548407f9e
Reviewed-on: https://go-review.googlesource.com/c/go/+/214424
Reviewed-by: Bryan C. Mills <bcmills@google.com>

src/cmd/go/go_test.go

@@ -2174,21 +2174,6 @@ func TestGoBuildGOPATHOrderBroken(t *testing.T) {
 	tg.run("install", "-x", "bar")
 }
 
-func TestIssue11709(t *testing.T) {
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.tempFile("run.go", `
-		package main
-		import "os"
-		func main() {
-			if os.Getenv("TERM") != "" {
-				os.Exit(1)
-			}
-		}`)
-	tg.unsetenv("TERM")
-	tg.run("run", tg.path("run.go"))
-}
-
 func TestGoBuildARM(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping cross-compile in short mode")

src/cmd/go/testdata/script/run_issue11709.txt

@@ -0,0 +1,15 @@
+# 'go run' should not pass extraneous environment variables to the subprocess.
+go run run.go
+! stdout .
+! stderr .
+
+-- run.go --
+package main
+
+import "os"
+
+func main() {
+	if os.Getenv("TERM") != "" {
+		os.Exit(1)
+	}
+}