build: pin brightnessctl in a persistent local Gentoo overlay

tests/test_image.py

@@ -298,6 +298,25 @@ class ImageBuildTests(unittest.TestCase):
             self.builder.rootfs()
         self.assertFalse(self.builder.manifest()['rootfs']['complete'])
 
+    def test_corrupt_local_package_archive_invalidates_fetch_checkpoint(self):
+        import hashlib
+        source = self.project / 'image'
+        source.mkdir()
+        (source / 'sources.json').write_text(json.dumps({
+            'stage3': {'url': 'https://example.test/stage.tar', 'sha256': hashlib.sha256(b'stage').hexdigest()},
+            'portage': {'url': 'https://example.test/repo.tar', 'sha256': hashlib.sha256(b'repo').hexdigest()},
+            'local_packages': [{'url': 'https://example.test/brightnessctl.tar.gz',
+                                'filename': 'brightnessctl.tar.gz', 'sha256': hashlib.sha256(b'original-source').hexdigest()}]}))
+        with self.builder.locked():
+            (self.builder.cache / 'stage.tar').write_bytes(b'stage')
+            (self.builder.cache / 'repo.tar').write_bytes(b'repo')
+            archive = self.builder.cache / 'brightnessctl.tar.gz'
+            archive.write_bytes(b'original-source')
+            self.builder.record('fetch')
+            self.assertTrue(self.builder.complete('fetch'))
+            archive.write_bytes(b'corrupted-source')
+            self.assertFalse(self.builder.complete('fetch'))
+
     def test_changed_canonical_patch_invalidates_package_input_identity(self):
         patches = self.project / 'patches'
         patches.mkdir()