Change mode of seafile-data directory



Seafile by default creates files with mode 0600.
This is very unfortunate as at least the group (I’m using seafile:seafile) should have read permissions.

Intention behind this:
My backup-Service connects remotely to the server using a backup-user which is member of the seafile group. This backup-job fails as it is unable to read all the commits due to 0600 permissions.

How can I change this behaviour in seafile?
(umask according to kernel is 0022 - so I can rule out this)

Thanks for any help.