OpenLDAP is marked incompatible in the packages.mask list. The reason is currently not known. The maintainer of this package is listed as: achim@gentoo.org achim does not currently have a bugzilla account.
achim doesn't maintain this package any more. Azarah might know what to do with this (or which packages are uncompatible with >=2).
It was masked before my time. I did test with a few stuff, but until we know what the original reason was for masking it, it will be difficult to mark to to resolved. I did ask on IRC, but nobody knew what the reason for this was.
I unmasked this. It was masked very long time ago, so, we can just drop this issue until we get reports of problem with this version.