[Routing] Strange behavior with default parameter

Given the following route :

@Route("/foo{bar}", defaults={"bar" = "ok"}, name="test")

And the following twig :

 {{ path('test') }}

The excepted result would be : "/foo"
But the result is :   "/fo"

I guess symfony remove an imaginary trailing slash or something like that ? Is this behavior excepted ? Is it a bug ? Am i doing something i'm not supposed to with this route ?
