Clean needed when turning a directory into a file

[voodoos]

Changing a directory test to a single-file test with the same name requires a dune clean:

Given a working directory cram test:
  $ mkdir sometest.t
  $ cat >sometest.t/run.t <<EOF
  >   $ echo "foobar"
  >   foobar
  > EOF

  $ dune build @sometest

We turn it into a single-file test:
  $ mv sometest.t sometest.t.bak
  $ mv sometest.t.bak/run.t sometest.t
  $ rm -r sometest.t.bak

FIXME: Dune should detect the change:
  $ dune build @sometest
  Error: _build/default/sometest.t: Is a directory
  -> required by _build/default/sometest.t
  -> required by alias sometest
  [1]

After a clean it works as expected:
  $ dune clean
  $ dune build @sometest

Specifications

• Version of dune: main (3.6.0-85-gdd6f976)

• Version of ocaml: 4.14

• Operating system: Macos (M1)

• Link to gist with verbose output (run dune with the --verbose flag):

[emillon]

See also #3753 for a similar issue in the past.