Segfault when unplugging during close verification

1)
Description: Ubuntu 14.04.3 LTS
Release: 14.04

2)
putty:
  Installed: 0.63-4ubuntu0.1
  Candidate: 0.63-4ubuntu0.1
  Version table:
 *** 0.63-4ubuntu0.1 0
        500 http://be.archive.ubuntu.com/ubuntu/ trusty-updates/universe amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ trusty-security/universe amd64 Packages
        100 /var/lib/dpkg/status
     0.63-4 0
        500 http://be.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages

3)
If you just unplug the usb you are connected to, putty closes down.
-> OK

4)
If you click the close button and unplug usb while the confirmation box is still on the screen, putty segfaults.
Should be easy to reproduce.

Best Regards