We try to load a module defined in an executable

  $ make_dune_project 3.3

  $ cat >bar.ml <<EOF
  > let v = 42
  > EOF

  $ cat >foo.ml <<EOF
  > let foo = Bar.v + 42
  > EOF

  $ cat >dune <<EOF
  > (executable
  >  (name foo))
  > EOF

  $ dune ocaml top-module foo.ml
  #directory "$TESTCASE_ROOT/_build/default/.topmod/foo.ml";;
  #load "$TESTCASE_ROOT/_build/default/.foo.eobjs/byte/dune__exe.cmo";;
  #load "$TESTCASE_ROOT/_build/default/.foo.eobjs/byte/dune__exe__Bar.cmo";;
  #load "$TESTCASE_ROOT/_build/default/.topmod/foo.ml/dune__exe__Foo.cmo";;
  open Dune__exe
  ;;

  $ ls _build/default/.topmod/foo.ml/
  dune__exe.cmi
  dune__exe__Bar.cmi
  dune__exe__Foo.cmi
  dune__exe__Foo.cmo

  $ dir=_build/default/.foo.eobjs/byte/
  $ ls $dir/*.cmi
  _build/default/.foo.eobjs/byte//dune__exe.cmi
  _build/default/.foo.eobjs/byte//dune__exe__Bar.cmi
  $ ls $dir/*.cmo
  _build/default/.foo.eobjs/byte//dune__exe.cmo
  _build/default/.foo.eobjs/byte//dune__exe__Bar.cmo
