Fix handling of four byte utf8 manifests

- Adds the charset: utf-8 to all the manifest responses
- Makes sure we connect to MySQL in utf8mb4 mode, to ensure we can properly read and write 4-byte utf8 strings
- Adds tests for all of the above

test/registry/registry_tests.py

@@ -1822,3 +1822,35 @@ def test_push_legacy_pull_not_allowed(v22_protocol, v1_protocol, remote_images,
   # Attempt to pull. Should fail with a 404.
   v1_protocol.pull(liveserver_session, 'devtable', 'newrepo', 'latest', remote_images,
                    credentials=credentials, expected_failure=Failures.UNKNOWN_TAG)
+
+
+def test_push_pull_emoji_unicode(pusher, puller, unicode_emoji_images, liveserver_session,
+                                 app_reloader):
+  """ Test: Push an image with unicode inside and then pull it. """
+  credentials = ('devtable', 'password')
+
+  # Push a new repository.
+  pusher.push(liveserver_session, 'devtable', 'newrepo', 'latest', unicode_emoji_images,
+              credentials=credentials)
+
+  # Pull the repository to verify.
+  puller.pull(liveserver_session, 'devtable', 'newrepo', 'latest', unicode_emoji_images,
+              credentials=credentials)
+
+
+def test_push_pull_emoji_unicode_direct(pusher, puller, unicode_emoji_images, liveserver_session,
+                                        app_reloader):
+  """ Test: Push an image with *unescaped* unicode inside and then pull it. """
+  credentials = ('devtable', 'password')
+
+  # Turn off automatic unicode encoding when building the manifests.
+  options = ProtocolOptions()
+  options.ensure_ascii = False
+
+  # Push a new repository.
+  pusher.push(liveserver_session, 'devtable', 'newrepo', 'latest', unicode_emoji_images,
+              credentials=credentials, options=options)
+
+  # Pull the repository to verify.
+  puller.pull(liveserver_session, 'devtable', 'newrepo', 'latest', unicode_emoji_images,
+              credentials=credentials, options=options)