Update User-Name AVP on Post Auth module

[Suriya Shankar]

Hello Everyone,
I am aware that It's not good to alter the User-Name  but I have a
requirement. I am authenticating an EAP_TTLS request and during the
Post-Auth section every module in the Unlang is being called by
*modcall_recurse*, one such is the policy module where I update the
User-Name along with other standard AVP in reply just to verify. As soon as
the control came back to the modcall.c *User-Name* value alone kept intact.
Is there some sort of callback or method handle that reverts back the
User-Name to its original.

Thanks,
Suriya