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Exit loudly if there are outstanding Fate operations. Since Fate serializes class names, we
need to make sure there are no queued transactions from a previous version before continuing an
upgrade. The status of the operations is irrelevant; those in SUCCESSFUL status cause the same
problem as those just queued.
Note that the Master should not allow write access to Fate until after all upgrade steps are
complete.
Should be called as a guard before performing any upgrade steps, after determining that an
upgrade is needed.
see ACCUMULO-2519