bug#7534: 24.0.50; G-g within Isearch regexp mode

[Dani Moncayo]

Recipe:
0) Start Emacs (-Q)
1) Place point at the beginning of the *scratch* buffer.
2) Search for the regexp "iss" (C-M-s iss) --> The last `s' is
unmatched as expected, OK.
3) Type C-g --> The unmatched part disappears. Everything OK so far.
4) Now repeat steps #2 and #3 with the regexp "is[". --> This time C-g
behaves differently. Instead of deleting the unmatched part, it ends
Isearch mode.


The fail seems to appear whenever `[' is the first character in the
unmatched part. For instance:
 * C-M-s iss[ C-g --> Works as expected (unmatched part deleted).
 * C-M-s is[blablabla --> Doesn't work as expected (Isearch cancelled).


-- 
Dani Moncayo