Nice! The change works.
One nitpick only. If you want to fix an existing constant string like 'on'. Do it with b'on' and not with ensure_bytes('on'). It is smaller and we use ensure_bytes() for complex cases only (like when you change existing dynamic variable 'ensure_bytes(very_dynamic_str_var)').

Also, you have a trailing whitespace here

First, please, mention in the commit description which test suites did you fix.
Also, mention the way you've fixed it ( explicitly changing strings to bytes).

And you need to rebase the commit with recent changes from master.

389-ds-base is moving from Pagure to Github. This means that new issues and pull requests
will be accepted only in 389-ds-base's github repository.

This pull request has been cloned to Github as issue and is available here:
- https://github.com/389ds/389-ds-base/issues/2681

If you want to continue to work on the PR, please navigate to the github issue,
download the patch from the attachments and file a new pull request.

Thank you for understanding. We apologize for all inconvenience.