string replace with multibyte chars and extglob fails with bash-4.2

[Mike Frysinger]

first set your locale to something unicode based:
export LC_ALL=en_US.UTF-8

then try the simple script (from Ulrich Müller):
$ cat test.sh
shopt -s extglob
text="aaaäöü"
echo "${text} ${text//?aa} ${text//\aaa}"

with bash-4.1_p2, i get:
aaaäöü äöü äöü

but with bash-4.2_p8 ... 4.2_p24 (just what i have locally):
aaaäöü aaaäöü aaaäöü

seems like a bug to me
-mike

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