Comment 5 for bug 1340728

I only tested it with the MEMORY engine, but I think it's enough since the problem isn't the type of engine or index itself, but the fact that MySQL 'explains' it won't use the primary key. (for whatever reason).

We should determine what the desired behaviour of "--nocheck-plan" should be, since without the patch it actually does check the PLAN in two other places in the code.

By the way, this should be considered just a hack for now.

(I'm uploading another smaller patch, since one of the checks in the previous one was redundant.)