Add one more check to test

Author: pakrym

test/Microsoft.AspNet.Http.Tests/ResponseCookiesTest.cs

@@ -14,10 +14,13 @@ public void DeleteCookieShouldSetDefaultPath()
         {
             var headers = new HeaderDictionary();
             var cookies = new ResponseCookies(headers);
+            var testcookie = "TestCookie";
 
-            cookies.Delete("TestCookie");
+            cookies.Delete(testcookie);
 
-            Assert.Contains("path=/", (string)headers[HeaderNames.SetCookie]);
+            string cookieHeaderValue = headers[HeaderNames.SetCookie];
+            Assert.StartsWith(testcookie, cookieHeaderValue);
+            Assert.Contains("path=/", cookieHeaderValue);
         }
 
     }