#0  strrchr () at ../sysdeps/i386/strrchr.S:178
#1  0x010546cb in __hurd_directory_name_split (
    use_init_port=0x104e8b0 <_hurd_ports_use>, 
    get_dtable_port=0x106cb40 <__getdport>, lookup=0, file_name=0x0, 
    name=0x1024c08) at hurdlookup.c:176
#2  0x01054838 in __directory_name_split (directory_name=0x0, name=0x1024c08)
    at hurdlookup.c:256
#3  0x01133ecc in __unlink (name=0x0) at ../sysdeps/mach/hurd/unlink.c:34
#4  0x0804ab33 in install_sudoers (oldperms=<optimized out>, 
    sp=<optimized out>)
    at /home/steven/sudo/sudo-1.8.3p1/plugins/sudoers/visudo.c:602
#5  main (argc=<optimized out>, argv=<optimized out>)
    at /home/steven/sudo/sudo-1.8.3p1/plugins/sudoers/visudo.c:253