modes not respected in combination with library with public_name

Expected Behavior

With a dune file such as:

(env
 (_
  (flags ())))

(subdir
 lib
 (library
  (name test_lib)
  (public_name test_package.test_lib)
  (modes native)))

(executable
 (name test_exe)
 (public_name test_exe)
 (package test_package)
 (libraries test_lib)
 (modes native))

I expect that executing dune build will not run ocamlc on implementation files. I realize that it might compile interface files with ocamlc even when building for native code only.

Actual Behavior

In the case above, dune build does run ocamlc on implementation files. Curiously, if (public_name test_package.test_lib) is removed, it does not.

Reproduction

Here is a small project that shows this: dune-bc-test.tar.gz

Specifications

• Version of dune (output of dune --version): 2.5
• Version of ocaml (output of ocamlc --version): 4.08.1
• Operating system (distribution and version): macos 10.14.6

Start by unpacking dune-bc-test.tar.gz and running dune build with the shown dune files to confirm the extra ocamlc compilation. Read the build actions for the interaction between public_name and modes, then add a regression test following HACKING.md. Done means native-only builds no longer compile implementation files with ocamlc in this case.