Hi!

I found a segfault bug on ZSH 5.2, but is confirmed that can be reproduced
in master.

Steps to reproduce:
1. Run a `zsh -f`
2. Set this config.
```
zstyle :compinstall filename "${HOME}/.zshrc"
autoload -Uz compinit
compinit
zstyle ':completion:*' menu select interactive
zstyle ':completion:*:warnings' format '%BNo matching %b%d'
unsetopt menu_complete auto_list
```
3. Start write a command. For example, write `ba`
4. Press tab to show options (interactive mode appears)
5. Write a letter that not mach with any option (to generate a completion
warning)
6. Press backspace

Tachan! zsh: segmentation fault (core dumped)

danielsh, on IRC, send this coredump:
http://sprunge.us/BXDU

Greetings.

-- 
Óscar García Amor | ogarcia@connectical.com
Connectical | http://connectical.com