As far as I can tell it isn't a hard dep and seeing how the other kids do it (e.g. kdelibs) krita should probably get in line and make it a useflag. Thanks...
Our dependencies need to be deterministic. If you want to have openexr support optional, ask for a configure flag at https://bugs.kde.org/
*** Bug 149459 has been marked as a duplicate of this bug. ***