[Resharper 4.1] Is this a bug? "Value assigned is not used in any execution path"

In this code, Resharper says that "flag = true" can be removed.

            bool flag = false;
            Action<Action> b = a =>
                       {
                           flag = true;
                           a();
                           flag = false;
                       };
            b(() => Console.WriteLine(flag));

Try it, and you will see that this changes the output of the program from "True" to "False".