keep it BindException

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@19983 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/TcpSlaveAgentListener.java

@@ -90,7 +90,7 @@ public final class TcpSlaveAgentListener extends Thread {
         try {
             serverSocket = new ServerSocket(port);
         } catch (BindException e) {
-            throw new IOException2("Failed to listen on port "+port+" because it's already in use.",e);
+            throw (BindException)new BindException("Failed to listen on port "+port+" because it's already in use.").initCause(e);
         }
         this.configuredPort = port;