filechooserbutton: Update the combo box even after the dialog is cancelled

filechooserbutton: Update the combo box even after the dialog is cancelled

We assumed that we didn't have to update the combo box if the dialog got cancelled,
as it should simply retain its previous contents.  But this assumption doesn't work
as the dialog is brought up with the 'Other...' item - we don't want the
combo box to keep showing 'Other...' if the dialog is cancelled.

The test from the previous commit now passes.

Signed-off-by: Federico Mena Quintero <federico@gnome.org>