Merge ~cjwatson/launchpad:py3-oci-registry-client into launchpad:master

[Colin Watson]

OCIRegistryClient: Fix bytes/text handling of JSON

On Python 3, `json.dumps` returns text, and prior to Python 3.6 `json.loads` required text input as well.

[Cristian Gonzalez (cristiangsp)]

Looks good!

review: Approve

diff --git a/lib/lp/oci/model/ociregistryclient.py b/lib/lp/oci/model/ociregistryclient.py
index e4aa271..3ba3348 100644
--- a/lib/lp/oci/model/ociregistryclient.py
+++ b/lib/lp/oci/model/ociregistryclient.py
@@ -80,7 +80,7 @@ class OCIRegistryClient:
         """Read JSON out of a `LibraryFileAlias`."""
         try:
             reference.open()
-            return json.loads(reference.read())
+            return json.loads(reference.read().decode("UTF-8"))
         finally:
             reference.close()
 
@@ -276,7 +276,7 @@ class OCIRegistryClient:
         # https://docs.docker.com/registry/spec/manifest-v2-2/#manifest-list
         # Specifically the Schema 2 manifest.
         digest = None
-        data = json.dumps(registry_manifest)
+        data = json.dumps(registry_manifest).encode("UTF-8")
         size = len(data)
         content_type = registry_manifest.get(
             "mediaType",
diff --git a/lib/lp/oci/tests/test_ociregistryclient.py b/lib/lp/oci/tests/test_ociregistryclient.py
index dcb2a8c..dcf71a8 100644
--- a/lib/lp/oci/tests/test_ociregistryclient.py
+++ b/lib/lp/oci/tests/test_ociregistryclient.py
@@ -285,7 +285,7 @@ class TestOCIRegistryClient(OCIConfigHelperMixin, SpyProxyCallsMixin,
 
         self.client.upload(self.build)
 
-        request = json.loads(responses.calls[1].request.body)
+        request = json.loads(responses.calls[1].request.body.decode("UTF-8"))
 
         self.assertThat(request, MatchesDict({
             "layers": MatchesListwise([