RTree keys are really different from BTree and need specific
paramters to be set by optimizer to work.
Sometimes optimizer doesn't set those properly.
Here we decided just to add code to check that the parameters
are correct. Hope to fix optimizer sometimes.
CHECK TABLE could complain about a fully intact spatial index.
A wrong comparison operator was used for table checking.
The result was that it checked for non-matching spatial keys.
This succeeded if at least two different keys were present,
but failed if only the matching key was present.
I fixed the key comparison.
