Default group memberships are not added when re-synced with user directory

Steps to Replicate:
1) Add a LDAP user directory with group and user management.
2) Choose the "Read Only, with Local Groups" option and add an internal group for "Default Group Memberships".
3) Sync with the LDAP server and note that the new user is made a member of the default group above, when they first log into Stash successfully.
4) Manually remove this group membership for this user via admin, ensuring they are no longer listed as a member of this local group.
5) Re-sync with LDAP server.

Result: The user is not added to the default internal group when resynced. Logging in again or otherwise does not make a difference.
Expected result: The default group membership should be added back after a resync.

• The same behaviour is noticed with delegated LDAP authentication as well.
• Also experienced with Stash given this setup: AD > JIRA (Remote with Local Groups) > Stash