kv_alloc guards every KVState free with if(k->Lc) precisely so it can be
called again on the same KVState (context resize, slot re-init). Exercise
that path: allocate, touch the cache, allocate again at a larger size.
Fails at this commit with a double-free (fixed in the next commit):
malloc: *** error for object 0x7: pointer being freed was not allocated
Michael Denyer