Contract polymorphism crashes on non-obvious child contract typing

[radrow]

Repro:

contract interface I =
  entrypoint f : () => int

contract C1 : I =
  entrypoint f() = 123

contract C2 : I =
  entrypoint f() = 888

namespace Make =
  stateful function new1() : I = Chain.create() : C1
  stateful function new2() : I = Chain.create() : C2

  stateful function new(c : I) : int =
    c.f()

This is caused by fcode compiler looking for bytecode of I for some reason (which doesn't make any sense since 1) it is not needed 2) it doesn't even exist).