bug#12254: 24.2; completion fails backward-char

[Leo]

This is a regression. It doesn't happen in Emacs 23.4.

1. Emacs -q -l b.el (b.el is attached)
2. M-x b-mode
3. Type I followed by <tab> to complete to IGNORE
4. C-b

In step 4, C-b could not move backwards; point appears to be trapped
there.

Leo

b.el
Description: b.el