Linux kernel repo: Error updating working copy: Unexpected object type from `git cat-file`

I think since commit “Fix an issue where ancestors of permanent refs might not be published…”: https://github.com/phacility/phabricator/commit/06edcf270921a9d5c1c4be3c006dfc15253506fa#diff-ddc9153181e873d938329e8ce7cf4e6a
Phabricator fails to update the working copy of our linux-stable repo. The error message is the following:
Error updating working copy: Unexpected object type from git cat-file: c39ae07f393806ccf406ef966e9a15afc43cc36a tree 736

This is a special object in the linux kernel tree:
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tag/?h=v2.6.11-tree

If I try to update the repository manually I get the following error:
Examining “v2.6.12” (tag) at “9ee1c939d1cb936b1f98e8d81aeffab57bae46ab”.
Skipping, HEAD is known.
Examining “v2.6.11-tree” (tag) at “c39ae07f393806ccf406ef966e9a15afc43cc36a”.
Skipping, this is not a commit.
Examining “v2.6.11” (tag) at “c39ae07f393806ccf406ef966e9a15afc43cc36a”.
Skipping, this is not a commit.
[2020-06-24 11:35:00] EXCEPTION: (Exception) Unexpected object type from git cat-file: c39ae07f393806ccf406ef966e9a15afc43cc36a tree 736 at [/src/applications/diffusion/query/lowlevel/DiffusionLowLevelResolveRefsQuery.php:160]
arcanist(head=stable, ref.master=f4c80a114d36, ref.stable=a798e740719b), phabricator(head=stable, ref.stable=d5a7d4081daa), sprint(head=wmf/stable, ref.master=9da8f6c3f272, ref.wmf/stable=7f34f377a425)
#0 DiffusionLowLevelResolveRefsQuery::resolveGitRefs() called at [/src/applications/diffusion/query/lowlevel/DiffusionLowLevelResolveRefsQuery.php:41]
#1 DiffusionLowLevelResolveRefsQuery::executeQuery() called at [/src/applications/diffusion/query/lowlevel/DiffusionLowLevelQuery.php:23]
#2 DiffusionLowLevelQuery::execute() called at [/src/applications/repository/engine/PhabricatorRepositoryRefEngine.php:245]
#3 PhabricatorRepositoryRefEngine::removeMissingCommits(array) called at [/src/applications/repository/engine/PhabricatorRepositoryRefEngine.php:92]
#4 PhabricatorRepositoryRefEngine::updateRefs() called at [/src/applications/repository/management/PhabricatorRepositoryManagementUpdateWorkflow.php:141]
#5 PhabricatorRepositoryManagementUpdateWorkflow::updateRepositoryRefs(PhabricatorRepository) called at [/src/applications/repository/management/PhabricatorRepositoryManagementUpdateWorkflow.php:78]
#6 PhabricatorRepositoryManagementUpdateWorkflow::execute(PhutilArgumentParser) called at [/src/parser/argument/PhutilArgumentParser.php:492]
#7 PhutilArgumentParser::parseWorkflowsFull(array) called at [/src/parser/argument/PhutilArgumentParser.php:377]
#8 PhutilArgumentParser::parseWorkflows(array) called at [/scripts/repository/manage_repositories.php:22]

Version Info:
image

Does anybody have seen a similar behavior using a Linux kernel repo?

Any hint would be highly appreciated.

Thx,
Hannes

Sounds like a re-run of https://secure.phabricator.com/T11180 from 2016. Also T11301.
Eventually, we’ll collect all possible things that can be tagged.