Fix linked exception forming

There was a variable usage error in that 'exc_infos'
does not need to be three and also the exc_info[2] does
not need to be not-none if there is no traceback (which
is a valid usage/case of exc_info).

Change-Id: Iddb979e5cb7df424ee218854e0c766e5b45e3e29
Merge "Fix linked exception forming"