read this: https://github.com/angular/angular.js/blob/727b232fb2e2440b762c9ed1b9b8ae32e7a54f7d/src/ng/compile.js#L242

transclude is a sibling scope of directive scope, but it inherits from parent scope and it does not matter what type(inherit or isolate) directive scope is.

look here: https://github.com/angular/angular.js/blob/727b232fb2e2440b762c9ed1b9b8ae32e7a54f7d/src/ng/compile.js#L929