Auto combobox width broken since v4.0.9?

When select options are specified via ‘data’ field, like in
data: {…},
the width of combobox was automatically calculated up to version 4.0.8 of select2.
Starting from v4.0.9 the width is now minimal, so items do not fit, it looks like this:

I did not understand, what change from this list v4.0.9 changelog caused this and how can I fix it?