Comment 0 for bug 1334991

this is being found on particular systems

the issue can be reproduce on those systems with any usb3 flash drivers with following commands

$ ./usr/lib/2013.com.canonical.certification:checkbox/bin/removable_storage_test -s 268400000 -m 500000000 usb --driver xhci_hcd
Found the following mounted usb partitions:
    /dev/sdb1 : /media/u/C936-1EB6 : 5000000000 bits/s
--------------------
/dev/sdb1 (Total Data Size / iteration: 255.9662 MB):
 [Iteration 0] Average Speed: 5.5610
 Summary:
  Total Data Attempted: 255.9662 MB
  Total Time to write: 46.0287 secs
  Average Write Time: 46.0287 secs
  Average Write Speed: 5.5610 MB/s
Traceback (most recent call last):
  File "./removable_storage_test", line 628, in <module>
    sys.exit(main())
  File "./removable_storage_test", line 605, in main
    'xhci' == test.rem_disks_xhci[disk]):
KeyError: '/dev/sdb1'