The quota check doesn't work correctly

I have a quota per role set to 1 for some content type and role. I create one instance of this content type and all goes well. However, when I try to make changes to this same instance of content type, quota_by_role jumps in and tells that I can't create any new content but this makes no sense. One would think that if you are allowed to create 1 instance of some content type, one could edit that instance with out any limitations. Only if he tries to make NEW instance of it, he should be denied..

Otherwise quota_by_role seems to work fine, good job!