Needs to use ref syntax with GtkListStore (Vala 0.36)

I was packaging 3.25.1 for Fedora and came across a build failure:

valac '-d' 'src/simple-scan@exe' '-C' '--target-glib' ' 2.38' '--pkg' 'glib-2.0' '--pkg' 'gtk+-3.0' '--pkg' 'zlib' '--pkg' 'cairo' '--pkg' 'gdk-pixbuf-2.0' '--pkg' 'gusb' '--pkg' 'sane-backends' '--pkg' 'colord' '--pkg' 'packagekit-glib2' '--gresources=../src/simple-scan.gresource.xml' '--pkg=posix' '--vapidir=/builddir/build/BUILD/simple-scan-3.25.1/src' '-D' 'HAVE_COLORD' '-D' 'HAVE_PACKAGEKIT' ../src/config.vapi ../src/book.vala ../src/book-view.vala ../src/page.vala ../src/page-view.vala ../src/simple-scan.vala ../src/scanner.vala ../src/ui.vala ../src/autosave-manager.vala
../src/ui.vala:470.42-470.45: error: Argument 1: Cannot pass value to reference or output parameter
                    device_model.remove (iter);
                                         ^^^^
../src/ui.vala:483.34-483.37: error: Argument 1: Cannot pass value to reference or output parameter
            device_model.remove (iter);
                                 ^^^^
Compilation failed: 2 error(s), 0 warning(s)
ninja: build stopped: subcommand failed.

It seems that Vala now (there is 0.36.1 in Fedora) expects those to be ref arguments.