Fix cursor renewal with LevelDB backend.
Fix cursor renewal with LevelDB backend.

Bad assertions, bad assumptions. Cursors don't have to be reset before being renewed, unlike transactions.

Also fixes what might have been a memory leak...

feld/stronglink,feld/stronglink,nkatsaros/stronglink,guiquanz/stronglink,rmoorman/stronglink,shaunstanislaus/stronglink,iOSCowboy/stronglink,guiquanz/stronglink,feld/stronglink,btrask/stronglink,yamingd/stronglink,iOSCowboy/stronglink,Lacra17/stronglink,iOSCowboy/stronglink,btrask/stronglink,shaunstanislaus/stronglink,Ryezhang/stronglink,Lacra17/stronglink,btrask/stronglink,Ryezhang/stronglink,shaunstanislaus/stronglink,Ryezhang/stronglink,Lacra17/stronglink,yamingd/stronglink,nkatsaros/stronglink,nkatsaros/stronglink,yamingd/stronglink,guiquanz/stronglink,btrask/stronglink,rmoorman/stronglink,rmoorman/stronglink