Improve `handle_commit` test in sandbox.
Improve `handle_commit` test in sandbox.

exonum/exonum,alekseysidorov/exonum,alekseysidorov/exonum,exonum/exonum,alekseysidorov/exonum,alekseysidorov/exonum,exonum/exonum,exonum/exonum