fix(tests): u1e hands the wrapper its own python - PATH's python3 may lack paho (Issue #60, Linux item 4)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_issue50_dispatch.py

@@ -165,9 +165,11 @@ def test_u1e_a_dry_run_record_is_not_an_open_job(tmp_path):
     admission must not wait for it."""
     reg = tmp_path / "jobs"
     # WORKSPACE_ROOT: the wrapper sources lib.sh, which otherwise writes the
-    # checkout's own .mam/shim/herdr (Issue #17 follow-up; W1 runs this node)
+    # checkout's own .mam/shim/herdr (Issue #17 follow-up; W1 runs this node).
+    # DELEGATE_JOB_PYTHON: from tmp_path the wrapper finds no .venv and would
+    # take PATH's python3, which may lack paho (Issue #60, Linux).
     env = dict(os.environ, HOME=str(tmp_path), MAM_ENV_FILE=str(tmp_path / ".mam.env.absent"),
-               WORKSPACE_ROOT=str(tmp_path))
+               WORKSPACE_ROOT=str(tmp_path), DELEGATE_JOB_PYTHON=sys.executable)
     res = subprocess.run(["bash", str(WRAPPER), "submit", "--agent", "human", "--agent-session", "herdr:s",
                           "--dry-run", "--registry-dir", str(reg), "--prompt", "preview only"],
                          capture_output=True, text=True, env=env, cwd=str(tmp_path), timeout=120)