Bug#3234: nvi segfaults if stty rows 0 columns 0

[Ian Jackson <ian@chiark.chu.cam.ac.uk>]

Package: nvi
Version: 1.34-12

-chiark:~> stty rows 38 columns 80
-chiark:~> vi
-chiark:~> stty rows 0 columns 0
-chiark:~> vi
Segmentation fault
-chiark:~> ll /etc/alternatives/vi
lrwxrwxrwx   1 root     root           12 Jun  6 02:36 /etc/alternatives/vi -> /usr/bin/nvi*
-chiark:~> dpkg -l nvi
Desired=Unknown/Install/Remove/Purge
| Status=Not/Installed/Config-files/Unpacked/Failed-config/Half-installed
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name            Version        Description
+++-===============-==============-============================================
ii  nvi             1.34-12        4.4BSD re-implementation of vi.
-chiark:~>

I can reproduce this at will; let me know if you need the coredump.

Ian.