Does searching with missing group attributes raise exceptions?

[consideRatio]

From #165 (comment):

I found that it was due to the allowed_groups testing the "memberOf" attribute, as the LDAP server only has the memberUid option, and the attempted search of LDAP3 on memberOf raises an exception now. This either needs a try.. except in the LDAP administrator, or the ability to specify which of the three group searches to try.

That to me sounds like a somewhat clear description of a bug, but I'm not sure if its still relevant. If it is, it should be something we should fix.