Description of problem:
virt-manager continues to use a usb device (usb-stick) after it has been physically removed and replaced with another usb-stick.  Restarting virt-manager fixes the problem.

Version-Release number of selected component (if applicable):
Fedora 21, virt-manager--1.1.0-3.git310f6527 plus patch 
commit 3e5a20aaf13b97b2afe4415d3557dae74f89eaf7

How reproducible:
everytime

Steps to Reproduce:
1.create virtual and attach usb-stick as usb host device, run virtual
2.show virtual down and remove the usb-stick
3.insert new (2nd) usb stick into the same usb port
4.same virtual; add hardware usb host device
5.show the old (removed) usb stick

Actual results:
Still shows the first usb-stick

Expected results:
Would now have the new usb-stick

Additional info:
If you boot anyway, you get error starting domain. Did not find usb device