Function isBusy

fdbserver/VersionedBTree.actor.cpp:1371–1373

	}

	bool isBusy() {
		return headWriter.isBusy() || headReader.isBusy() || tailWriter.isBusy() || !newTailPage.isReady();
	}

	// Wait until all previously started operations on each cursor are done and the new tail page is ready
	Future<Void> notBusy() {