ovs-vsctl: /var/run/ovs-vswitchd.*.ctl is a Unix domain socket

ovs-vsctl: /var/run/ovs-vswitchd.*.ctl is a Unix domain socket

Currently ov-vsctl tries to treat /var/run/ovs-vswitchd.*.ctl as a
file/pipe when it is actually a Unix domain socket:

        # ovs-vsctl add-br TEST
        Traceback (most recent call last):
          File "/usr/bin/ovs-vsctl", line 498, in ?
            main()
          File "/usr/bin/ovs-vsctl", line 493, in main
            function(*args)
          File "/usr/bin/ovs-vsctl", line 345, in cmd_add_br
            cfg_save(cfg, VSWITCHD_CONF)
          File "/usr/bin/ovs-vsctl", line 142, in cfg_save
            cfg_reload()
          File "/usr/bin/ovs-vsctl", line 126, in cfg_reload
            f = open(target, "r+")
        IOError: [Errno 6] No such device or address: ' '
        # ls -l /var/run/ovs-vswitchd.4173.ctl
        srw------- 1 root root 0 Sep 14 12:25 /var/run/ovs-vswitchd.4173.ctl

From strace:
        open("/var/run/ovs-vswitchd.4173.ctl", O_RDWR|O_LARGEFILE) = -1 ENXIO (No such device or address)