$ dune build @uninstall-mandir
File "test/blackbox-tests/test-cases/uninstall-mandir.t/run.t", line 1, characters 0-0:
------ test/blackbox-tests/test-cases/uninstall-mandir.t/run.t
++++++ test/blackbox-tests/test-cases/uninstall-mandir.t/run.t.corrected
File "test/blackbox-tests/test-cases/uninstall-mandir.t/run.t", line 58, characters 0-1:
 |  Installing install/man/man1/test.1
 |
 |-------------------------------------------------------------------------------
 |Simulate another tool being installed and creating some manpages in the prefix
 |
 |  $ mkdir -p install/man/man1 && touch install/man/man1/foobar
 |
 |-------------------------------------------------------------------------------
 |Uninstall the project; since the manpage directory contains pages from other
 |tools, dune should not remove it, nor complain about it being non-empty.
 |
 |  $ dune uninstall --prefix=install -p test test | dune_cmd sanitize
 |  Deleting install/lib/test/META
 |  Deleting install/lib/test/dune-package
 |  Deleting install/lib/test/opam
 |  Deleting install/man/man1/test.1
-|  Deleting empty directory install/lib/test
+|  Error: Please delete non-empty directory install/man/man1 manually.
 |