https://github.com/NixOS/nix/pull/9917 (Enter debugger more reliably in let expressions and function calls)

This test ensures that continues don't skip opportunities to enter the debugger.
  trace: before outer break
  info: breakpoint reached

  nix-repl> :c
  trace: before inner break
  info: breakpoint reached

  nix-repl> :c

  nix-repl> msg
  "hello"