continue_on_fail=true fake A-leg hangup cause

scenario:

FS/1 <> ASTPP <> FS/2

A call hangup UNALLOCATED_NUMBER from FS/2
ASTPP get UNALLOCATED_NUMBER and FS/1 CDR get NORMAL_CLEARING.

i found 3 solutions
1) disable continue_on_fail putting on gateway variables continue_on_fail=false (this don't allow work fail over system astpp)
2) use continue_on_fail with specific hangup cause for failover
3) add to freeswitch/scrips/astpp/scripts/astpp.xml.lua:freeswitch_xml_outbound at the end

table.insert(xml, [[<action application="hangup" data="${last_bridge_hangup_cause}"/>]])