Adding helm charts leaves tmp files behind in tmp dir of blobstore

We noticed that the blobstore directory of our helm chart repos is growing and growing. Deleting and compacting all helm charts did not really reduce the size. Investigation revealed that the ./tmp directory in the blob store directory of the helm chart blob is growing and growing. Files added there seem never be removed. Since we build a lot of helm charts every day, within a few weeks the directory grows to several gigabytes.

How to reproduce?

Start a fresh copy of Nexus 3.30.0 (e.g. from docker). Add a blob store and repository for self hosted helm charts. Add some random helm chart via the upload menu. 

Expected result

The  blobs/helm/content/tmp dir should not grow

Actual result

Every time a helm chart gets added, some files are created in the tmp directory and nevery cleaned up. Not when compacting the repo, deleting the helm chart or restarting Nexus.