[2.2.x] Fixed #30647 -- Fixed crash of autoreloader when extra directory cannot be resolved.

Backport of fc75694257 from master.

django/utils/autoreload.py

@@ -235,8 +235,15 @@ class BaseReloader:
 
     def watch_dir(self, path, glob):
         path = Path(path)
-        if not path.is_absolute():
-            raise ValueError('%s must be absolute.' % path)
+        try:
+            path = path.absolute()
+        except FileNotFoundError:
+            logger.debug(
+                'Unable to watch directory %s as it cannot be resolved.',
+                path,
+                exc_info=True,
+            )
+            return
         logger.debug('Watching dir %s with glob %s.', path, glob)
         self.directory_globs[path].add(glob)
 

django/utils/translation/reloader.py

@@ -13,8 +13,7 @@ def watch_for_translation_changes(sender, **kwargs):
         directories.extend(Path(config.path) / 'locale' for config in apps.get_app_configs())
         directories.extend(Path(p) for p in settings.LOCALE_PATHS)
         for path in directories:
-            absolute_path = path.absolute()
-            sender.watch_dir(absolute_path, '**/*.mo')
+            sender.watch_dir(path, '**/*.mo')
 
 
 def translation_file_changed(sender, file_path, **kwargs):

docs/releases/2.2.4.txt

@@ -21,3 +21,6 @@ Bugfixes
 
 * Fixed a regression in Django 2.2 where auto-reloader crashes if a file path
   contains nulls characters (``'\x00'``) (:ticket:`30506`).
+
+* Fixed a regression in Django 2.2 where auto-reloader crashes if a translation
+  directory cannot be resolved (:ticket:`30647`).

tests/utils_tests/test_autoreload.py

@@ -515,6 +515,12 @@ class BaseReloaderTests(ReloaderTests):
         watched_files = list(self.reloader.watched_files())
         self.assertIn(self.existing_file, watched_files)
 
+    def test_watch_dir_with_unresolvable_path(self):
+        path = Path('unresolvable_directory')
+        with mock.patch.object(Path, 'absolute', side_effect=FileNotFoundError):
+            self.reloader.watch_dir(path, '**/*.mo')
+        self.assertEqual(list(self.reloader.directory_globs), [])
+
     def test_watch_with_glob(self):
         self.reloader.watch_dir(self.tempdir, '*.py')
         watched_files = list(self.reloader.watched_files())