In a construct like this:

var=foo
readonly var
for num in 1 2 3 4 5
do
if [ $num -eq 3 ]
then
var=bar
fi 
echo $num
done

the loop breaks in the third round, after trying to set the r/o variable. Particularly an issue, when looping the the scripts in profile.d, should a variable be set twice by accident or if the scripts are sourced again by a script.

Latest version accessible:
~/test > bash --version
GNU bash, version 4.2.24(1)-release (x86_64-pc-linux-gnu)
on Ubuntu Precise.