pkg/expect: sends SIGTERM to the cmd process on close()

etcd process won't terminateon SIGINT
but will on SIGTERM if test is run as a background process.
related issue etcd-io#725.

pkg/expect/expect.go

@@ -23,6 +23,7 @@ import (
 	"os/exec"
 	"strings"
 	"sync"
+	"syscall"
 
 	"github.com/kr/pty"
 )
@@ -140,7 +141,9 @@ func (ep *ExpectProcess) close(kill bool) error {
 		return ep.err
 	}
 	if kill {
-		ep.Signal(os.Interrupt)
+		// go runtime ignores SIGINT but not SIGTERM
+		// if e2e test is run as a background process.
+		ep.Signal(syscall.SIGTERM)
 	}
 
 	err := ep.cmd.Wait()