Backport of 8343 is missing partially in 8349

CMS 2.24.xx (7.8) is missing #46748 from issue CMS7-8347. This should have been covered in CMS7-8349.

Below error message is shown in terminal when I login with "qa admin" and remember me enabled.

[INFO] [talledLocalContainer] 14.10.2014 16:26:37 ERROR [org.hippoecm.frontend.plugins.login.RememberMeLoginPlugin$SignInForm.login():417] javax.jcr.query.InvalidQueryException: Lexical error at line 1, column 40. Encountered: "_" (95), after : "" for statement: for $v in //element(*, hipposys:user)qa_x005f_x0020_admin'] return $v.