ALF-679: Corrected regular expression matching logic in DefaultRemoteUserMapper

git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@19986 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/web/app/servlet/DefaultRemoteUserMapper.java

@@ -207,6 +207,10 @@ public class DefaultRemoteUserMapper implements RemoteUserMapper, ActivateableBe
             {
                 userId = matcher.group(1).trim();
             }
+            else
+            {
+                return null;                
+            }
         }
         return userId.length() == 0 ? null : userId;
     }