GitLab creates artifact directories on disk although S3 is configured

Summary

We switched from artifact storage on disk to s3. But GitLab keeps creating directory structures below /var/opt/gitlab/gitlab-rails/shared/artifacts - no files are created, only directories.

Artifacts directory was deleted after the migration. All directories listed below have been created after the migration to s3:

/var/opt/gitlab/gitlab-rails/shared/artifacts# ls
02  0a  0b  11  16  18  1a  1e  22  26  28  29  2d  2f  32  34  35  38  45  49  4c  4d  59  61  62  66  67  6e  6f  70  72  78  7f  80  82  86  88  8a  8e  98  9f  a1  aa  ae  b4  ba  bb  bc  c0  c1  c5  c6  c9  ca  cb  ce  cf  d8  dc  df  ec  ed  f2  f5  f8  fc  tmp
/var/opt/gitlab/gitlab-rails/shared/artifacts# find . -type f

Steps to reproduce

Not perfectly sure, but I can state what we did. We migrated our artifacts storage from disk to s3. Using the migration tool.

gitlab-rake gitlab:artifacts:migrate

When uploading artifacts to s3 GitLab creates directories below the default path for artifacts on disk.

Example Project

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What is the current bug behavior?

When uploading artifacts to s3 GitLab creates directories below the default path for artifacts on disk.

What is the expected correct behavior?

No directories should be created when uploading artifacts to s3. If gitlab needs a temporary directory to cache the artifact before uploading it - the directories should be cleaned up after the upload.

Relevant logs and/or screenshots

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Output of checks

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Results of GitLab environment info

System information
System:		Ubuntu 18.04
Current User:	git
Using RVM:	no
Ruby Version:	2.6.3p62
Gem Version:	2.7.9
Bundler Version:1.17.3
Rake Version:	12.3.3
Redis Version:	3.2.12
Git Version:	2.22.2
Sidekiq Version:5.2.7
Go Version:	unknown

GitLab information
Version:	12.5.4
Revision:	63af04cacf5
Directory:	/opt/gitlab/embedded/service/gitlab-rails
DB Adapter:	PostgreSQL
DB Version:	10.9
URL:		<redacted>
HTTP Clone URL:	<redacted>
SSH Clone URL:	<redacted>
Using LDAP:	<redacted>
Using Omniauth:	<redacted>
Omniauth Providers: <redacted>

GitLab Shell
Version:	10.2.0
Repository storage paths:
- default: 	/var/opt/gitlab/git-data/repositories
GitLab Shell path:		/opt/gitlab/embedded/service/gitlab-shell
Git:		/opt/gitlab/embedded/bin/git

Results of GitLab application Check

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