When bone meal is used on a berry bush at its final stage, it drops berries and goes back 2 stages

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What I expected to happen:

It would stop being affected by bone meal and I could break it to harvest the berries.

What actually happened:

I can use bonemeal on it forever, with it dropping berries every 3 bone meal uses.

How to reproduce:

1. Plant a berry bush
2. Constantly use bone meal on it