container/run: Fix TestRunAttachTermination

Restore part of the code removed by 966b44183f
that closed the stream. It's required now because the Run command won't
finish before the output stream was processed by the caller.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

cli/command/container/run_test.go

@@ -147,6 +147,7 @@ func TestRunAttachTermination(t *testing.T) {
 		_ = p.Close()
 	}()
 
+	var conn net.Conn
 	killCh := make(chan struct{})
 	attachCh := make(chan struct{})
 	fakeCLI := test.NewFakeCli(&fakeClient{
@@ -163,6 +164,7 @@ func TestRunAttachTermination(t *testing.T) {
 		},
 		containerAttachFunc: func(ctx context.Context, containerID string, options container.AttachOptions) (types.HijackedResponse, error) {
 			server, client := net.Pipe()
+			conn = server
 			t.Cleanup(func() {
 				_ = server.Close()
 			})
@@ -202,6 +204,7 @@ func TestRunAttachTermination(t *testing.T) {
 	}
 
 	assert.NilError(t, syscall.Kill(syscall.Getpid(), syscall.SIGTERM))
+	conn.Close()
 
 	select {
 	case <-killCh: