bug#26125: ispell fails to detect certain typos

[Leon Meier]

Used packages:
- auctex 11.90.0,
- emacs 24.3.1 (24.3-22.1 on OpenSuse),
- ispell 3.3.02 (3.3.02-113.1 on OpenSuse),
- ispell-american (american.aff v 1.23, 3.3.02-113.1 on OpenSuse)

Bug description:

Create the file q.tex with the following contents (without the square 
brackets):
[
\(\sigma\) contradition

%%% Local Variables:
%%% ispell-local-dictionary: "american"
%%% End:
]

Then, open q.tex with emacs when auctex is loaded. Issue
M-x ispell-buffer <RET>

Observe that the typo in the word "contradition" remains unnoticed.

With auctex 11.87-11.42, taken from opensuse leap 42.2 by default, the 
bug is not present: the typo "contradition" is correctly reported.

Any bugfix?

Thx in advance,
Leon