How to change DList elements by means of foreach?

[Alexandr Druzhinin]

I have code:

import std.container;

int main() {
// array
int[] array = [0];
foreach(ref value; array) {
        value += 50;
        assert(value == 50);
}

foreach(value; array) {
        assert(value == 50);
}       

// double-linked list;
DList!int dlist;
dlist.insertFront(0);
foreach(ref value; dlist) {
        value += 50;
        assert(value == 50);
}

foreach(value; dlist) {
        assert(value == 50);  // Why do I have assertion failure here?
}

}
How to change the value of elements of DList?