Fix Packet#add_header: first binding key was always forced to binding value. In case on parsing a packet, at least one binding is already set, and this force may cause to change another one, which make parsing bad.
Fix Packet#add_header: first binding key was always forced to binding value.
In case on parsing a packet, at least one binding is already set, and this
force may cause to change another one, which make parsing bad.

Fix: only force previous header key if no key is already set.

sdaubert/packetgen