Try to untangle the logic in server_port_flush

Try to untangle the logic in server_port_flush

It's a bit confusing to have a loop where another function,
confusingly named "*_free", is responsible for advancing the loop
variable (or rather, for altering a structure so that the next time
the loop variable's initializer is evaluated it evaluates to something
different.)

Not only has this confused people: it's also confused coverity scan.
Let's fix that.