merlin 4.2 + OCaml 4.12 + dune 2.8 seems broken when using (include_subdirs unqualified). Concretely, given a dune file in applications/apropos/addins/dune containing (include_subdirs unqualified), when editing the file applications/apropos/addins/models/local_vol_hull_white_model.mf I get:

No config found for file "local_vol_hull_white_model.mf" in "applications\\apropos\\addins\\models". Try calling `dune build`.

(This is under Windows).

cc @voodoos