Fix ordering of tags in the OCI model

Before this change, we were neglecting to sort the tags by ID, which meant that pagination was broken

data/registry_model/test/test_interface.py

@@ -936,3 +936,37 @@ def test_unicode_emoji(registry_model):
   assert found.digest == manifest.digest
   assert found.internal_manifest_bytes.as_encoded_str() == manifest.bytes.as_encoded_str()
   assert found.get_parsed_manifest().digest == manifest.digest
+
+
+def test_list_repository_tags(oci_model):
+  repository_ref = oci_model.lookup_repository('devtable', 'simple')
+  latest_tag = oci_model.get_repo_tag(repository_ref, 'latest')
+  manifest = oci_model.get_manifest_for_tag(latest_tag)
+
+  tag_count = 500
+
+  # Create a bunch of tags.
+  tags_expected = set()
+  for index in range(0, tag_count):
+    tags_expected.add('somenewtag%s' % index)
+    oci_model.retarget_tag(repository_ref, 'somenewtag%s' % index, manifest, storage)
+
+  # List the tags.
+  tags_found = set()
+  tag_id = None
+  while True:
+    tags = oci_model.list_repository_tags(repository_ref, start_pagination_id=tag_id,
+                                          limit=11, sort_tags=True)
+    assert len(tags) <= 11
+    for tag in tags[0:10]:
+      assert tag.name not in tags_found
+      if tag.name in tags_expected:
+        tags_expected.remove(tag.name)
+
+    if len(tags) < 11:
+      break
+
+    tag_id = tags[10].id
+
+  # Make sure we've found all the tags.
+  assert not tags_expected