Adding child commit to repository fails with "parent commit could not be loaded"

[achilleas-k]

Version
pulpcore version: 3.31.0
pulp-ostree version: 2.1.1

Describe the bug
Importing a child commit to a repository fails with The parent commit '<PARENT COMMIT ID>' could not be loaded, even though the parent commit is already in the repository.

To Reproduce
I have an ostree repository in Pulp with a single commit under the ref test/iot. I created a child commit using osbuild-composer.

Status checks:

1. Check pulp repository commit ID with curl

$ curl http://localhost:8080/pulp/content/pulptest/refs/heads/test/iot
86b2ffaf4d90b23bea660d9bb9fd5416baafd2df56331e92f4a715abb3e27ca2

with ostree summary

$ mkdir repo
$ cd repo
$ ostree init --repo .
$ ostree remote add test http://localhost:8080/pulp/content/pulptest/
$ ostree remote summary test
* test/iot
    Latest Commit (18.9 kB):
      86b2ffaf4d90b23bea660d9bb9fd5416baafd2df56331e92f4a715abb3e27ca2
    Version (ostree.commit.version): 38
    Timestamp (ostree.commit.timestamp): 2023-08-21T14:07:21+02

Last-Modified (ostree.summary.last-modified): 2023-08-21T14:10:14+02
Repository Mode (ostree.summary.mode): archive-z2
Has Tombstone Commits (ostree.summary.tombstone-commits): No
ostree.summary.indexed-deltas: true

2. Check the child commit ID and parent

With commit.tar being the child tarball built by image builder:

$ mkdir child
$ tar xvf commit.tar -C child
$ ostree show --repo ./child/repo test/iot
commit 89b1f4ae4a587212a2bd366058607ecd92f129c8ddd9cf5f5f50ca3819e0ce4d
Parent:  86b2ffaf4d90b23bea660d9bb9fd5416baafd2df56331e92f4a715abb3e27ca2
ContentChecksum:  5aaeab2ecae71861e61ace7e32ca0ee8e85e1824b566cb979fd612889f5079e1
Date:  2023-08-21 12:22:50 +0000
Version: 38
(no subject)

3. Upload child commit to pulp.

$ pulp -v ostree repository import-all --file ./commit.tar --name test-repo --repository_name repo
repositories_ostree_ostree_list : get http://localhost:8080/pulp/api/v3/repositories/ostree/ostree/?name=test-repo&offset=0&limit=1
Response: 200
artifacts_list : get http://localhost:8080/pulp/api/v3/artifacts/?sha256=c1992bc1350cca8246f7bc8d9152a3d52c033470d56ba85ae7f4c160440fdb53&offset=0&limit=1
Response: 200
Artifact already exists.
repositories_ostree_ostree_import_all : post http://localhost:8080/pulp/api/v3/repositories/ostree/ostree/018a17fe-f2c9-74b4-a6eb-5b3325fadb4e/import_all/
Response: 202
tasks_read : get http://localhost:8080/pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/
Response: 200
Started background task /pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/
.tasks_read : get http://localhost:8080/pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/
Response: 200
.tasks_read : get http://localhost:8080/pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/
Response: 200
.tasks_read : get http://localhost:8080/pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/
Response: 200
.tasks_read : get http://localhost:8080/pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/
Response: 200
.tasks_read : get http://localhost:8080/pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/
Response: 200
.tasks_read : get http://localhost:8080/pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/
Response: 200
Error: Task /pulp/api/v3/tasks/018a1836-9086-7184-a831-7760e9dc69d1/ failed: 'The parent commit '86b2ffaf4d90b23bea660d9bb9fd5416baafd2df56331e92f4a715abb3e27ca2' could not be loaded'

Expected behavior
The child commit should import successfully and become the new commit for the test/iot ref.

Additional context
The following appears in the pulp container log

pulp [46ae9e063c7f48f3ba203de5ac4e632b]: pulpcore.tasking.tasks:INFO: Task 018a1836-9086-7184-a831-7760e9dc69d1 failed (The parent commit '86b2ffaf4d90b23bea660d9bb9fd5416baafd2df56331e92f4a715abb3e27ca2' could not be loaded)
pulp [46ae9e063c7f48f3ba203de5ac4e632b]: pulpcore.tasking.tasks:INFO:   File "/usr/local/lib/python3.8/site-packages/pulpcore/tasking/tasks.py", line 65, in _execute_task
    result = func(*args, **kwargs)

  File "/usr/local/lib/python3.8/site-packages/pulp_ostree/app/tasks/importing.py", line 49, in import_all_refs_and_commits
    return dv.create()

  File "/usr/local/lib/python3.8/site-packages/pulpcore/plugin/stages/declarative_version.py", line 161, in create
    loop.run_until_complete(pipeline)

  File "/usr/lib64/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()

  File "/usr/local/lib/python3.8/site-packages/pulpcore/plugin/stages/api.py", line 220, in create_pipeline
    await asyncio.gather(*futures)

  File "/usr/local/lib/python3.8/site-packages/pulpcore/plugin/stages/api.py", line 41, in __call__
    await self.run()

  File "/usr/local/lib/python3.8/site-packages/pulp_ostree/app/tasks/importing.py", line 301, in run
    parsed_result = await self.parse_ref(name, ref_commit_checksum)

  File "/usr/local/lib/python3.8/site-packages/pulp_ostree/app/tasks/importing.py", line 114, in parse_ref
    raise ValueError(

[achilleas-k]

Here's a standalone reproducer:

#!/usr/bin/env bash

set -euo pipefail

workdir=$(mktemp -d)
cd "${workdir}"

# prepare pulp
pulp ostree repository create --name test
pulp ostree distribution create --name test --repository test --base-path test

# first commit
mkdir "${workdir}/first"
cd "${workdir}/first"
ostree --repo="${workdir}/first/repo" init --mode=archive
mkdir "${workdir}/first/files"
echo "one" > files/file.txt
commit=$(ostree commit --repo "${workdir}/first/repo" --branch ostree-main "${workdir}/first/files/")

cd "${workdir}/first"
tar czvf repo.tar "repo/"

# first upload
pulp ostree repository import-all --name test --file repo.tar --repository_name repo

# second commit
mkdir "${workdir}/second"
cd "${workdir}/second"
mkdir files
echo "two" > files/file2.txt
ostree --repo="${workdir}/second/repo" init --mode=archive
ostree commit --repo repo --branch ostree-main files/ --parent="${commit}"
tar czvf repo.tar repo/

# second upload
echo "Uploading and importing second repo"
pulp ostree repository import-all --name test --file repo.tar --repository_name repo  # Error: Task /pulp/api/v3/tasks/.../ failed: 'The parent commit '...' could not be loaded'