outputs 'env activate' verbose message on stderr

Author: deronnax

src/poetry/console/application.py

@@ -581,7 +581,7 @@ def configure_env(self, event: Event, event_name: str, _: EventDispatcher) -> No
         env = env_manager.create_venv()
 
         if env.is_venv() and io.is_verbose():
-            io.write_line(f"Using virtualenv: <comment>{env.path}</>")
+            io.write_error_line(f"Using virtualenv: <comment>{env.path}</>")
 
         command.set_env(env)
 

tests/console/commands/test_run.py

@@ -91,7 +91,10 @@ def test_run_passes_args_after_run_before_command_name_conflict(
     path.rename(path.parent / "run")
 
     app_tester.execute(f"{args} python -V", decorated=True)
-    assert app_tester.io.fetch_error() == ""
+    assert (
+        app_tester.io.remove_format(app_tester.io.fetch_error())
+        == f"Using virtualenv: {env.path}\n"
+    )
     assert env.executed == [["python", "-V"]]