Panic with usb serial

[Vince]

Hi all,
	Is it expected that removing a usb serial adapter while you have a 
connection (eg tip) using it will panic a -stable system? I know it is 
expected if you remove a mounted umass device so wanted to see if its 
known behavior for serial before I file a pr. (adapter is <FTDI usb 
serial converter, class 0/0, rev 1.10/4.00, addr 3>)
-stable version as of the 25th march, (may have existed before but the 
first time I forgot to close tip before removing the device was on this 
version.)


cheer,
Vince