User Search searches in too many fields

If you search for a user in the user in the users control panel it is possible to get results that do not seem to be correct.
Tested on the gogreen:
1. Login as admin
2. Go to the user control panel
3. Search for r2 or something else

Expected result:
Find author20 and editor20.

Observed result:
Find author15, author20, editor16 and editor20.

Longest I could search for with incorrect results is QCHsXMNHbakKORNln8PvKeXf2oU to find admin11. This is part of the password.
Wildcards are not necessary as you will find every user if you search for "internal" as this is the securityprovider. Bit this could be intended.