A workspace with a package that exists in the lock file and in the workspace
shouldn't be allowed (for now)

  $ . ./helpers.sh

  $ cat >dune-project <<EOF
  > (lang dune 3.11)
  > EOF

  $ touch mypkg.opam
  $ mkdir dune.lock
  $ cat >dune.lock/lock.dune <<EOF
  > (lang package 0.1)
  > EOF
  $ touch dune.lock/mypkg.lock

  $ dune build

It should also fail when we define the package only in the dune-project file:

  $ rm mypkg.opam
  $ cat >>dune-project <<EOF
  > (package
  >  (allow_empty)
  >  (name mypkg))
  > EOF

  $ dune build
