Fix automsummary directive wrong processing for invalid modules.

sphinx/ext/autosummary/__init__.py

@@ -302,8 +302,7 @@ class Autosummary(SphinxDirective):
                 with mock(self.config.autosummary_mock_imports):
                     real_name, obj, parent, modname = import_by_name(name, prefixes=prefixes)
             except ImportError:
-                logger.warning(__('failed to import %s'), name)
-                items.append((name, '', '', name))
+                logger.warning(__('autosummary: failed to import %s'), name)
                 continue
 
             self.bridge.result = StringList()  # initialize for each documenter

tests/test_ext_autosummary.py

@@ -397,7 +397,7 @@ def test_autosummary_template(app):
                     confoverrides={'autosummary_generate': []})
 def test_empty_autosummary_generate(app, status, warning):
     app.build()
-    assert ("WARNING: autosummary: stub file not found 'autosummary_importfail'"
+    assert ("WARNING: autosummary: failed to import autosummary_importfail"
             in warning.getvalue())