xmlrpc server: delete function on errors

xmlrpc server: delete function on errors

This patch makes sure to delete an idle function that
raises an exception for the xmlrpc server.

The counterpart functionality in the process server was
added with:

commit db50630948394bdcd361f3511af40c1896b1a017.
duthor: Richard Purdie <richard.purdie@linuxfoundation.org>
Date:   Wed Aug 20 22:31:06 2014 +0000

    bitbake: process: Deal with infinite looping of the server

This patch fixes

[YOCTO #7316]

Signed-off-by: Alexandru DAMIAN <alexandru.damian@intel.com>