Fix check for used DNs

hello,

taken from limux-gosa git commit 14bdb21c5b5c313a261f1578f9158cffcfd1c659

Cheers

(from redmine: issue id 1050, created on 2012-06-12, closed on 2012-11-30)

• Changesets:
  • Revision f43ec05a by Benoit MORTIER on 2012-06-12T17:23:37.000Z:

Fixes: #1050 Fix check for used DNs

• Custom Fields:
  • Bug in version: 1.0.4