title: haproxy use_backend condition (acl) is missing the backend
body: <p>I have an application which I installed in two servers for balancing issue.</p>
  
  <p>I wanted to route the traffic like below:</p>
  
  <p>server 1: client
  server 2: admin</p>
  
  <p>server 1 app config:
  host: 192.168.0.101
  port: 5031</p>
  
  <p>server 2 app config:
  host: 192.168.0.102
  port: 5032</p>
  
  <p>Application is same in both servers with same database connection.</p>
  
  <p>I installed haproxy in 192.168.0.101 with port 5033 and setup:</p>
  
  <pre><code>frontend hh-test
          bind 192.168.0.101:5033
          mode tcp
          option tcplog
          acl is_admin path_reg ^/admin/sales$
          use_backend server2 if is_admin
          default_backend server1
  
  backend server2
          mode tcp
          server admin 192.168.0.102:5032
  
  backend server1
          mode tcp
          server client 192.168.0.101:5031
  </code></pre>
  
  <p>It does work. When I access <a href="http://192.168.0.101:5033" rel="nofollow noreferrer">http://192.168.0.101:5033</a> It serves from Server 1 and when I access <a href="http://192.168.0.101:5033/admin/sales" rel="nofollow noreferrer">http://192.168.0.101:5033/admin/sales</a> it serves from server2 ...as expected. But some request goes to server1 accessing same /admin/sales url. Very few. I am not sure what I am doing wrong that some request goes to the other backend. Can I have an insight please?</p>