Issue #14938: importlib.abc.SourceLoader.is_package() now takes the

module name into consideration when determining whether a module is a
package or not. This prevents importing a module's __init__ module
directly and having it considered a package, which can lead to
duplicate sub-modules.

Thanks to Ronan Lamy for reporting the bug.

2 files changed, 6 insertions, 3 deletions

diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 6656db3..117c0f6 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -578,7 +578,9 @@ class _LoaderBasics:
         """Concrete implementation of InspectLoader.is_package by checking if
         the path returned by get_filename has a filename of '__init__.py'."""
         filename = _path_split(self.get_filename(fullname))[1]
-        return filename.rsplit('.', 1)[0] == '__init__'
+        filename_base = filename.rsplit('.', 1)[0]
+        tail_name = fullname.rpartition('.')[2]
+        return filename_base == '__init__' and tail_name != '__init__'
 
     def _bytes_from_bytecode(self, fullname, data, bytecode_path, source_stats):
         """Return the marshalled bytes from bytecode, verifying the magic
diff --git a/Lib/importlib/test/source/test_abc_loader.py b/Lib/importlib/test/source/test_abc_loader.py
index b1b1204..fc98b93 100644
--- a/Lib/importlib/test/source/test_abc_loader.py
+++ b/Lib/importlib/test/source/test_abc_loader.py
@@ -602,10 +602,11 @@ class SourceOnlyLoaderTests(SourceLoaderTestHarness):
 
     def test_is_package(self):
         # Properly detect when loading a package.
-        self.setUp(is_package=True)
-        self.assertTrue(self.loader.is_package(self.name))
         self.setUp(is_package=False)
         self.assertFalse(self.loader.is_package(self.name))
+        self.setUp(is_package=True)
+        self.assertTrue(self.loader.is_package(self.name))
+        self.assertFalse(self.loader.is_package(self.name + '.__init__'))
 
     def test_get_code(self):
         # Verify the code object is created.