I have generated with form.fields_for and
form.grouped_collection_select
the following html (this is just sample):
when user submit form, in log i have params[:car][:name] = “Swedish
Cars”
i did not success to reproduce this issue … except replacing one of
“option”'s value with “Swedish Cars”
But optgroup in normal situation should not be selected … maybe IE9
bug ? (i dont know what browser was that)