diff -r 293d9964cf6e Lib/unittest/loader.py
--- a/Lib/unittest/loader.py	Tue Apr 28 00:04:53 2015 -0400
+++ b/Lib/unittest/loader.py	Tue Apr 28 11:46:20 2015 +0300
@@ -126,7 +126,10 @@
         tests = self.suiteClass(tests)
         if load_tests is not None:
             try:
-                return load_tests(self, tests, pattern)
+                # load_tests may call loader.discover which changes self._top_level_dir
+                _top_level_dir = self._top_level_dir
+                tests = load_tests(self, tests, pattern)
+                self._top_level_dir = _top_level_dir
             except Exception as e:
                 error_case, error_message = _make_failed_load_tests(
                     module.__name__, e, self.suiteClass)
@@ -451,9 +454,6 @@
                         msg % (mod_name, module_dir, expected_dir))
                 return self.loadTestsFromModule(module, pattern=pattern), False
         elif os.path.isdir(full_path):
-            if (not namespace and
-                not os.path.isfile(os.path.join(full_path, '__init__.py'))):
-                return None, False
 
             load_tests = None
             tests = None
diff -r 293d9964cf6e Lib/unittest/test/test_discovery.py
--- a/Lib/unittest/test/test_discovery.py	Tue Apr 28 00:04:53 2015 -0400
+++ b/Lib/unittest/test/test_discovery.py	Tue Apr 28 11:46:20 2015 +0300
@@ -53,7 +53,7 @@
             os.path.isdir = original_isdir
 
         path_lists = [['test2.py', 'test1.py', 'not_a_test.py', 'test_dir',
-                       'test.foo', 'test-not-a-module.py', 'another_dir'],
+                       'test.foo', 'test-not-a-module.py', 'another_dir'], [],
                       ['test4.py', 'test3.py', ]]
         os.listdir = lambda path: path_lists.pop(0)
         self.addCleanup(restore_listdir)
@@ -65,7 +65,7 @@
 
         def isfile(path):
             # another_dir is not a package and so shouldn't be recursed into
-            return not path.endswith('dir') and not 'another_dir' in path
+            return not path.endswith('dir')
         os.path.isfile = isfile
         self.addCleanup(restore_isfile)
 
@@ -85,7 +85,7 @@
         # The test suites found should be sorted alphabetically for reliable
         # execution order.
         expected = [[name + ' module tests'] for name in
-                    ('test1', 'test2', 'test_dir')]
+                    ('another_dir', 'test1', 'test2', 'test_dir')]
         expected.extend([[('test_dir.%s' % name) + ' module tests'] for name in
                     ('test3', 'test4')])
         self.assertEqual(suite, expected)