test(issue-17): the failing wait-rc test sources the wrapper in its own WORKSPACE_ROOT

Sourcing the wrapper sources lib.sh, which writes $WORKSPACE_ROOT/.mam/shim/
herdr; without WORKSPACE_ROOT that is the checkout. The new N2 wait-rc test
now runs with its tmp dir as WORKSPACE_ROOT, so the N2 tests leave the
checkout untouched. (The existing C tests in this file still write the
checkout's .mam/shim/herdr, as at 56d0bfd - not changed here.)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HCGpJXhSZasJLU38ksDghe

tests/test_issue17_item4_decisions.py

@@ -689,7 +689,7 @@ def test_f_a_failed_wait_rc_ends_wait_with_1(tmp_path, mode):
     py = _failing_py(tmp_path, "wait-rc", mode)
     script = f'source "{WRAPPER}"; PY="{py}"; set +e; (cmd_wait --job j1 --timeout 5); echo "rc=$?"'
     res = subprocess.run(["bash", "-c", script], capture_output=True, text=True, cwd=str(tmp_path), timeout=60,
-                         env=_env(tmp_path, SUB_STANDIN=1, SUB_RC=4, DELEGATE_JOB_PYTHON=py))
+                         env=_env(tmp_path, SUB_STANDIN=1, SUB_RC=4, DELEGATE_JOB_PYTHON=py, WORKSPACE_ROOT=tmp_path))
     assert "rc=1" in res.stdout, (res.stdout, res.stderr[-800:])
     assert "ERROR: the wrapper could not decide 'wait-rc'" in res.stderr, res.stderr[-800:]