Find out why TestProof fails (tree root never seems to match here).
It's not clear why this is a race-condition. Either 1) fix test, 2) clarify why it is skipped, or 3) remove test (only if the test does not make sense).

https://github.com/tendermint/iavl/blob/35f66e53d9b01e83b30de68b931f54b2477a94c9/basic_test.go#L392-L422