Import: .py module wins over namespace-package dir (#10614)

When both `foo/` (no __init__.py) and `foo.py` existed on the
filesystem, `import foo` silently imported the empty namespace package
and skipped `foo.py`. CPython picks the `.py` in this case, and the
docs define that precedence: regular package > module > namespace
package.

stat_module now probes for `__init__.py`/`.mpy` inside the directory
first, then falls back to `.py`/`.mpy`, and only treats the bare
directory as a namespace package when neither exists.

Adds a native_sim regression test and extends the test harness so
`circuitpy_drive` can include files inside subdirectories.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: tannewt

ports/zephyr-cp/tests/conftest.py

@@ -289,12 +289,22 @@ def circuitpython(request, board, sim_id, native_sim_binary, native_sim_env, tmp
             tmp_drive = tmp_path / f"drive{i}"
             tmp_drive.mkdir(exist_ok=True)
 
+            created_dirs: set[str] = set()
             for name, content in files.items():
                 src = tmp_drive / name
+                src.parent.mkdir(parents=True, exist_ok=True)
                 if isinstance(content, bytes):
                     src.write_bytes(content)
                 else:
                     src.write_text(content)
+                parent = Path(name).parent
+                if parent != Path("."):
+                    parts = parent.parts
+                    for depth in range(1, len(parts) + 1):
+                        sub = "/".join(parts[:depth])
+                        if sub not in created_dirs:
+                            subprocess.run(["mmd", "-i", str(flash), f"::{sub}"], check=True)
+                            created_dirs.add(sub)
                 subprocess.run(["mcopy", "-i", str(flash), str(src), f"::{name}"], check=True)
 
         trace_file = tmp_path / f"trace-{i}.perfetto"

ports/zephyr-cp/tests/test_basics.py

@@ -92,6 +92,28 @@ def test_ctrl_c_interrupt(circuitpython):
     assert "completed" not in output
 
 
+IMPORT_PRECEDENCE_CODE = """\
+import fake_lib
+print("done")
+"""
+
+
+@pytest.mark.circuitpy_drive(
+    {
+        "code.py": IMPORT_PRECEDENCE_CODE,
+        "fake_lib/a_spritesheet.bmp": b"",
+        "fake_lib.py": 'print("hello fake_lib.py")\n',
+    }
+)
+def test_py_file_wins_over_namespace_dir(circuitpython):
+    """#10614: a .py module beats a sibling directory lacking __init__.py."""
+    circuitpython.wait_until_done()
+
+    output = circuitpython.serial.all_output
+    assert "hello fake_lib.py" in output
+    assert "done" in output
+
+
 RELOAD_CODE = """\
 print("first run")
 import time

py/builtinimport.c

@@ -105,7 +105,26 @@ static mp_import_stat_t stat_module(vstr_t *path) {
     mp_import_stat_t stat = stat_path(path);
     DEBUG_printf("stat %s: %d\n", vstr_str(path), stat);
     if (stat == MP_IMPORT_STAT_DIR) {
-        return stat;
+        // CIRCUITPY-CHANGE: match CPython import precedence. A regular
+        // package (directory with __init__.py/.mpy) takes precedence, then a
+        // sibling .py/.mpy module, and only then a namespace package
+        // (directory without __init__). See
+        // https://docs.python.org/3/reference/import.html#regular-packages
+        size_t orig_len = path->len;
+        vstr_add_str(path, PATH_SEP_CHAR "__init__.py");
+        mp_import_stat_t init_stat = stat_file_py_or_mpy(path);
+        path->len = orig_len;
+        if (init_stat == MP_IMPORT_STAT_FILE) {
+            return MP_IMPORT_STAT_DIR;
+        }
+
+        vstr_add_str(path, ".py");
+        mp_import_stat_t file_stat = stat_file_py_or_mpy(path);
+        if (file_stat == MP_IMPORT_STAT_FILE) {
+            return file_stat;
+        }
+        path->len = orig_len;
+        return MP_IMPORT_STAT_DIR;
     }
 
     // Not a directory, add .py and try as a file.