Description of problem:
1. Connect your scanner via USB
2. Open simple scan and scan a page
3. Disconnect your scanner and then reconnect it
4. Try scanning again
5. Simple scan crashes

Version-Release number of selected component:
simple-scan-3.16.2-1.fc22

Additional info:
reporter:       libreport-2.6.2
backtrace_rating: 4
cmdline:        simple-scan
crash_function: __pthread_mutex_lock
executable:     /usr/bin/simple-scan
global_pid:     2486
kernel:         4.1.5-200.fc22.x86_64
runlevel:       N 5
type:           CCpp
uid:            1000

Truncated backtrace:
Thread no. 1 (10 frames)
 #0 __pthread_mutex_lock at ../nptl/pthread_mutex_lock.c:67
 #1 libusb_set_interface_alt_setting at core.c:1556
 #2 sanei_usb_set_altinterface at sanei_usb.c:3076
 #3 sanei_usb_clear_halt at sanei_usb.c:2209
 #4 usb_dev_close at xerox_mfp-usb.c:95
 #5 sane_dll_close at dll.c:1223
 #6 sane_close at dll-s.c:78
 #7 scanner_close_device at /home/bob/bzr/simple-scan/3.16/src/scanner.vala:766
 #8 scanner_fail_scan at /home/bob/bzr/simple-scan/3.16/src/scanner.vala:780
 #9 _scanner_scan_thread_gthread_func at /home/bob/bzr/simple-scan/3.16/src/scanner.vala:1233