<select> ng-options cannot "track by" a string when "orderBy" filter is used

[SteveShaffer]

When using a comprehension expression for a element's ngOptions, I cannot use both a "track by" clause and the "orderBy" filter if I'm tracking by a string. But tracking by a number seems to work. Actually, everything seems to bind correctly under the hood, but the element won't show the value in the UI.

Works as expected in version 1.2.1 but doesn't work in 1.3.4.

See this jsFiddle: http://jsfiddle.net/27by0nmt/2/

Might be related to #7544.

[lgalfaso]

The plunker uses the wrong syntax. It should be ng-options="opt.label for opt in options | orderBy:['value'] track by opt.label"