Fix places where path needs to be bytes on python3

These were discovered on python3 with fetch code that fails on errors.  Probably could be
provoked with particular sets of arguments to stat as well.

test/units/module_utils/test_basic.py

@@ -647,7 +647,7 @@ class TestModuleUtilsBasic(ModuleTestCase):
         )
 
         def _mock_ismount(path):
-            if path == '/':
+            if path == b'/':
                 return True
             return False
 
@@ -655,7 +655,9 @@ class TestModuleUtilsBasic(ModuleTestCase):
             self.assertEqual(am.find_mount_point('/root/fs/../mounted/path/to/whatever'), '/')
 
         def _mock_ismount(path):
-            if path == '/subdir/mount':
+            if path == b'/subdir/mount':
+                return True
+            if path == b'/':
                 return True
             return False