bin/47809: su(1) with "-" switch segfaults on return.

[brad.harder%gmail.com@localhost]

>Number:         47809
>Category:       bin
>Synopsis:       su(1) with "-" switch segfaults on return.
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu May 09 02:15:00 +0000 2013
>Originator:     Brad Harder
>Release:        netbsd -current (6.99.19)
>Organization:
method logic digital
>Environment:
NetBSD kamloops 6.99.19 NetBSD 6.99.19 (GENERIC) #160: Wed May  8 16:05:24 PDT 
2013  root@kamloops:/usr/obj/sys/arch/amd64/compile/GENERIC amd64
>Description:
su(1) with "-" switch segfaults on return.

>How-To-Repeat:
kamloops$ su -
 Password:
Terminal type is screen.                                                        
                                                                                
                                                                                
                                kamloops# exit
[1]   Segmentation fault      su -
kamloops$ su
  Password:
kamloops# exit
kamloops$

>Fix: