This behaviour contradicts with description found in docs (in which
       <source> tag specify interface in host, not in container). I think,
       the previous bridge must be specified as
         <interface type='bridge'>
           <mac address='00:16:3e:34:21:9e'/>
       -     <source bridge='eth10'/>
       +     <target dev='eth10'/>
         </interface>

   You are right. It is bug.

Well, here is the patch, that fixes that behaviour.

Your patch is half of fix. It require to fix openvzReadNetworkConf() in
openvz_conf.c.