Description of problem:
Consoles get scrambled and unusable if two clients try to connect
at same time to the console.

Version-Release number of selected component (if applicable):
libvirt-0.9.4-17.el6.x86_64

How reproducible:
always

Steps to Reproduce:
1. append 'console=ttyS0,115200' to guest kernel cmdline in grub.conf
2. reboot guest
3. open a terminal and run virsh console $guest
4. open another terminal and run virsh console $guest
6. run other shell command such as 'ls' in the first terminal
  
Actual results:
Output information is incomplete in these 2 terminals.

Expected results:
if a client has opened the console, and the other clients should get a notice rather than continue to allow connect the console, it will let 2 clients confusion, especially, if these 2 clients are a remote users.

Additional info:
Maybe, There are 2 solutions for this issue:
1. Document these stuff in virsh man page or other place such as libvirt.org
2. Get a notice if the console is alive.

Solution 2 should be very nice.