pip installed module build fails.

From https://github.com/dune-project/dune-testpypi/actions/runs/17075749734/job/48416639400

ERROR: multiple definition of module dune-common
previous defined in:
  /home/runner/work/dune-testpypi/dune-testpypi/test/dune-env/lib/dunecontrol/dune-common/lib/dunecontrol/dune-common/dune.module
redefined in:
  /home/runner/work/dune-testpypi/dune-testpypi/test/dune-env/lib64/dunecontrol/dune-common/lib/dunecontrol/dune-common/dune.module
Execution of dunecontrol terminated due to errors!