Issue in User Search: Use of underscores works for admins, not for normal users

Prerequisites:

  1. at least one user with a username like “abc_” exists, e.g. abc_de
  2. the abc_de user is member of a group, e.g. “customers”.
  3. a test user exists, who has group-management permissions for the “customers” group
  4. the test user is not an admin user.

Steps to reproduce

  1. As an admin user, go to the users management and search for “abc_”.
  2. Do the same, as the test user

Expected behaviour

Both the admin user and the test user should find the abc_de user in the search result

Actual behaviour

Only the admin user finds abc_de

Server configuration

Linux (chroot environment)

Web server:
Apache 2.4
Database:
MySQL
PHP version:
7
ownCloud version: (see ownCloud admin page)
10.0.8.5
Updated from an older ownCloud or fresh install:
Fresh install
Where did you install ownCloud from:
Installed by hosting provider (owncube)
Signing status (ownCloud 9.0 and above):
Fine, except for my personal theme-app

Results
=======
- theme-seal
	- EXCEPTION
		- OC\IntegrityCheck\Exceptions\MissingSignatureException
		- Signature data not found.

The content of config/config.php:
Can be provided if relevant.

Are you using external storage, if yes which one: local/smb/sftp/…
No.

Are you using encryption: yes/no
No.

Are you using an external user-backend, if yes which one: LDAP/ActiveDirectory/Webdav/…
No.

Client configuration

Browser:
Firefox, Chrome

Operating system:
Windows 10

Hey,

have you considered to update to a more recent / stable version of ownCloud already available?