FunctionalTest : session problem

In a FunctionalTest, sessions aren't restore between 2 requests.
For instance, after a login request, and a homepage get,
the login response will contains a different session of the homepage get response.

This is a use case in the Chat sample application :

import java.io.File;
import java.util.HashMap;
import java.util.Map;

import org.junit.*;

import play.Logger;
import play.mvc.Http.*;
import play.test.*;

public class BugUseCase extends FunctionalTest {

 private void displayCookies(Map<String,Cookie> cookies) {
  for (String key : cookies.keySet())
   Logger.info("%s = %s",key, cookies.get(key).value);
 }

 @Test
 public void usecase () {
  GET("/logout"); // clear session

  Map<String, String> args = new HashMap<String, String>();
  args.put("nick", "toto");

  Response loginResponse = POST("/signin", args, new HashMap<String,File>()); // Login
  displayCookies(loginResponse.cookies);

  Response r = GET("/"); // Get main page
  displayCookies(r.cookies);

  assertEquals(loginResponse.cookies.get("PLAY_SESSION").value, r.cookies.get("PLAY_SESSION").value); // fail !
  assertIsOk(r); // Failure, Response status expected:<200> but was:<302> (in fact the login has failed)
 }
}

log :

14:26:14,145 INFO ~ PLAY_FLASH =
14:26:14,145 INFO ~ PLAY_ERRORS =
14:26:14,145 INFO ~ PLAY_SESSION = d94b6eaa6b58710ef950f0bb4943fb335c8c2a3b-%00___ID%3A3a336fa4-fcc7-42a1-ba97-792ed3d8f5df%00%00nick%3Atoto%00
14:26:14,154 INFO ~ PLAY_FLASH =
14:26:14,154 INFO ~ PLAY_ERRORS =
14:26:14,154 INFO ~ PLAY_SESSION = e6ff5f33bfc19e35727688654b69c8818e6a3734-%00___ID%3Af36df216-9154-4690-832c-62e01c444211%00

in the test page :

Failure, expected:<[d94b6eaa6b58710ef950f0bb4943fb335c8c2a3b-%00___ID%3A3a336fa4-fcc7-42a1-ba97-792ed3d8f5df%00%00nick%3Atoto]%00> but was:<[e6ff5f33bfc19e35727688654b69c8818e6a3734-%00___ID%3Af36df216-9154-4690-832c-62e01c444211]%00>

Best regards,
Gaetan Renaudeau