Description of problem:
The guest with <interface type='client'> can not start.

Version-Release number of selected component (if applicable):
libvirt-3.2.0-5.el7.x86_64
qemu-kvm-rhev-2.9.0-5.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. modify the guest's xml to be with below interface xml:
# virsh edit rhel7.4
....
   <interface type='client'>
      <source address='127.0.0.1' port='5558'/>
    </interface>
.....

# virsh dumpxml rhel7.4 | grep /interface -B5
    <interface type='client'>
      <mac address='52:54:00:aa:89:43'/>
      <source address='127.0.0.1' port='5558'/>
      <model type='rtl8139'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>

2. # virsh start rhel7.4
error: Failed to start domain rhel7.4
error: internal error: qemu unexpectedly closed the monitor: 2017-05-17T07:31:57.652002Z qemu-kvm: -chardev pty,id=charserial0: char device redirected to /dev/pts/5 (label charserial0)
2017-05-17T07:31:57.688051Z qemu-kvm: -device rtl8139,netdev=hostnet0,id=net0,mac=52:54:00:aa:89:43,bus=pci.0,addr=0x3: Property 'rtl8139.netdev' can't find value 'hostnet0'

3.
# cat  /var/log/libvirt/libvirtd.log  | grep error
2017-05-17 07:33:35.127+0000: 8444: error : qemuMonitorIORead:588 : Unable to read from monitor: Connection reset by peer
2017-05-17 07:33:35.127+0000: 8444: error : qemuProcessReportLogError:1845 : internal error: qemu unexpectedly closed the monitor: 2017-05-17T07:33:35.081189Z qemu-kvm: -chardev pty,id=charserial0: char device redirected to /dev/pts/5 (label charserial0)
2017-05-17 07:33:35.127+0000: 8444: debug : qemuMonitorIO:745 : Error on monitor internal error: qemu unexpectedly closed the monitor: 2017-05-17T07:33:35.081189Z qemu-kvm: -chardev pty,id=charserial0: char device redirected to /dev/pts/5 (label charserial0)
2017-05-17 07:33:35.127+0000: 8444: debug : qemuMonitorIO:776 : Triggering error callback
2017-05-17 07:33:35.127+0000: 8444: debug : qemuProcessHandleMonitorError:341 : Received error on 0x7f43c82db000 'rhel7.4'
2017-05-17 07:33:35.127+0000: 8444: debug : qemuMonitorIO:745 : Error on monitor internal error: qemu unexpectedly closed the monitor: 2017-05-17T07:33:35.081189Z qemu-kvm: -chardev pty,id=charserial0: char device redirected to /dev/pts/5 (label charserial0)
2017-05-17 07:33:35.128+0000: 8448: debug : qemuMonitorSend:1046 : Send command resulted in error internal error: qemu unexpectedly closed the monitor: 2017-05-17T07:33:35.081189Z qemu-kvm: -chardev pty,id=charserial0: char device redirected to /dev/pts/5 (label charserial0)
2017-05-17 07:33:35.328+0000: 8448: error : qemuProcessReportLogError:1845 : internal error: process exited while connecting to monitor: 2017-05-17T07:33:35.081189Z qemu-kvm: -chardev pty,id=charserial0: char device redirected to /dev/pts/5 (label charserial0)
2017-05-17 07:33:35.332+0000: 8448: info : virDBusCall:1558 : DBUS_METHOD_ERROR: 'org.freedesktop.machine1.Manager.TerminateMachine' on '/org/freedesktop/machine1' at 'org.freedesktop.machine1' error org.freedesktop.machine1.NoSuchMachine: No machine 'qemu-1-rhel7.4' known


Actual results:
The guest with <interface type='client'> can not start, but the one with <interface type='server'> can start successfully.

Expected results:
The guest can start successfully and they can communicate with each other, and the qemu command line will be like this:
-netdev socket,listen=127.0.0.1:5558,id=hostnet0   .....------> the server
-netdev socket,connect=127.0.0.1:5558,id=hostnet0  .....-----------> the client

Additional info:
N/A