$ dune init project name $PWD 2>&1 | head -n 8
  Internal error, please report upstream including the contents of _build/log.
  Description:
    ("[as_in_source_tree_exn] called on something not in source tree",
     { t =
         External
           "$TESTCASE_ROOT"
     })
  Raised at Stdune__Code_error.raise in file