`stats bind-process` broken

[Patrick Hemmer]

With haproxy 1.9.6 the `stats bind-process` directive is not working. 
Every connection to the socket is going to a random process:

Here's a simple reproduction:
Config:
   global
       nbproc 3
       stats socket /tmp/haproxy.sock level admin
       stats bind-process 1

Testing:
   # for i in {1..5}; do socat - unix:/tmp/haproxy.sock <<< "show info" 
| grep Pid: ; done
   Pid: 33371
   Pid: 33373
   Pid: 33372
   Pid: 33373
   Pid: 33373

-Patrick